Cell Biology Introduction
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Questions and Answers

What is the basic unit of structure and function in living organisms?

  • Organ
  • Molecule
  • Cell (correct)
  • Tissue

    • What branch of biology deals with the study of structure and function of plant and animal cells?

  • Cytology (correct)
  • Botany
  • Biology
  • Microscopy

    • Who observed a thin slice of cork under the microscope and saw structures which he called cells?

  • Robert Hooke (correct)
  • Anton van Leeuwenhoek
  • Leeuwenhoek
  • Galileo

    • What is the term for a thin slice of any part of a structure?

    <p>Section</p> Signup and view all the answers

    What type of section is obtained when a structure is cut along its length?

    <p>Longitudinal section</p> Signup and view all the answers

    What is the purpose of the mirror in a microscope?

    <p>To reflect light through the specimen</p> Signup and view all the answers

    What is the formula to calculate magnification?

    <p>Observed size / Actual size</p> Signup and view all the answers

    What is the purpose of the condenser in a microscope?

    <p>To reflect light through the specimen</p> Signup and view all the answers

    What is the function of the coarse and fine adjustors in a microscope?

    <p>To focus the image</p> Signup and view all the answers

    What is the result of observing cells under a microscope?

    <p>Cells become magnified</p> Signup and view all the answers

    What is the term used to describe the study of structure and function of plant and animal cells?

    <p>Cytology</p> Signup and view all the answers

    Who is credited with the invention of the simplest microscope?

    <p>Unknown</p> Signup and view all the answers

    What did Robert Hooke observe under the microscope in 1665?

    <p>Dead cells</p> Signup and view all the answers

    What is the purpose of the stage in a microscope?

    <p>To hold the specimen</p> Signup and view all the answers

    What is the function of the eyepiece lens in a microscope?

    <p>To magnify the image</p> Signup and view all the answers

    What is the result of adjusting the coarse and fine adjustors in a microscope?

    <p>Changing the focus of the image</p> Signup and view all the answers

    What is the purpose of the objective lens in a microscope?

    <p>To magnify the image</p> Signup and view all the answers

    What is the effect of observing cells under a microscope?

    <p>Cells become magnified</p> Signup and view all the answers

    What is the term for the ratio of observed size to actual size?

    <p>Magnification</p> Signup and view all the answers

    What is the purpose of the condenser in a microscope?

    <p>To focus the light</p> Signup and view all the answers

    What is the significance of 1665 in the study of cells?

    <p>The year Robert Hooke observed cork cells</p> Signup and view all the answers

    What is the purpose of the lenses in a microscope?

    <p>To produce a greatly magnified image of the specimen</p> Signup and view all the answers

    What is the difference between a longitudinal section and a transverse section?

    <p>A longitudinal section is cut along the length, while a transverse section is cut across the structure</p> Signup and view all the answers

    What is the function of the mirror in a microscope?

    <p>To reflect light through the specimen</p> Signup and view all the answers

    What happens to cells when observed under a microscope?

    <p>They become magnified</p> Signup and view all the answers

    What is the purpose of the stage in a microscope?

    <p>To hold the specimen in place</p> Signup and view all the answers

    What is the term for the study of structure and function of plant and animal cells?

    <p>Cytology</p> Signup and view all the answers

    What is the formula to calculate magnification power?

    <p>Observed size / Actual size</p> Signup and view all the answers

    What is the purpose of the objective lens in a microscope?

    <p>To magnify the image</p> Signup and view all the answers

    What is the function of the eyepiece lens in a microscope?

    <p>To magnify the image</p> Signup and view all the answers

    What is the maximum magnification that the best light microscope can achieve?

    <p>1500X</p> Signup and view all the answers

    Who formulated the cell theory?

    <p>Matthias Schleiden and Theodor Schwann</p> Signup and view all the answers

    What is the main factor that determines the shape of a cell?

    <p>The function of the cell</p> Signup and view all the answers

    What is the size range of most cells?

    <p>10-100 microns</p> Signup and view all the answers

    What is the longest type of animal cell?

    <p>Nerve cell</p> Signup and view all the answers

    What is the shape of a pigment cell of the skin?

    <p>Branched</p> Signup and view all the answers

    What is the size of the smallest cell, PPLO?

    <p>0.1-0.5 microns</p> Signup and view all the answers

    What is the maximum magnification that can be achieved by a light microscope?

    <p>1500X</p> Signup and view all the answers

    What is the main factor that determines the shape of a cell?

    <p>The function it performs</p> Signup and view all the answers

    What is the range of sizes of most cells?

    <p>10-100 microns</p> Signup and view all the answers

    What is the shape of a nerve cell?

    <p>Elongated and branched</p> Signup and view all the answers

    Who formulated the cell theory?

    <p>Matthias Schleiden and Theodor Schwann</p> Signup and view all the answers

    What is the shape of a pigment cell of the skin?

    <p>Branched</p> Signup and view all the answers

    What is the size of the smallest cell, PPLO?

    <p>0.1-0.5 microns</p> Signup and view all the answers

    What is the maximum magnification that can be achieved by the best light microscope?

    <p>1500X</p> Signup and view all the answers

    What is the size of the largest cell in the animal kingdom?

    <p>Ostrich egg size</p> Signup and view all the answers

    Who formulated the cell theory?

    <p>Matthias Schleiden and Theodor Schwann</p> Signup and view all the answers

    What is the shape of a muscle cell?

    <p>Spindle</p> Signup and view all the answers

    What is the main factor that determines the shape of a cell?

    <p>The function it performs</p> Signup and view all the answers

    What is the size of the smallest cell, PPLO?

    <p>0.1-0.5 microns</p> Signup and view all the answers

    What is the shape of a nerve cell?

    <p>Elongated and branched</p> Signup and view all the answers

    What is the maximum magnification achieved by the best light microscope?

    <p>1500X</p> Signup and view all the answers

    What is the size range of most cells?

    <p>10-100 microns</p> Signup and view all the answers

    What determines the shape of a cell?

    <p>The cell's function</p> Signup and view all the answers

    What is the shape of a nerve cell?

    <p>Elongated and branched</p> Signup and view all the answers

    Who formulated the cell theory?

    <p>Matthias Schleiden and Theodor Schwann</p> Signup and view all the answers

    What is the shape of a red blood cell?

    <p>Discoidal or saucer-shaped</p> Signup and view all the answers

    What is the size of the largest cell in the animal kingdom?

    <p>Ostrich egg cell</p> Signup and view all the answers

    What type of organisms are made up of a single cell?

    <p>Unicellular organisms</p> Signup and view all the answers

    What is the main characteristic of a plasma membrane?

    <p>It is selectively permeable</p> Signup and view all the answers

    What is the term for the living substance of the cell?

    <p>Protoplasm</p> Signup and view all the answers

    What is the type of model that explains the structure and function of the plasma membrane?

    <p>Fluid mosaic model</p> Signup and view all the answers

    What is the type of organisms that viruses are considered to be?

    <p>Non-cellular organisms</p> Signup and view all the answers

    What is the term for the outermost layer of the cell?

    <p>Plasma membrane</p> Signup and view all the answers

    What is the main component of the plasma membrane?

    <p>Phospholipids and proteins</p> Signup and view all the answers

    What is the thickness of the plasma membrane?

    <p>Less than 1/10,000 mm</p> Signup and view all the answers

    What is the characteristic feature of unicellular organisms?

    <p>They are made up of a single cell</p> Signup and view all the answers

    What is the main component of a virus?

    <p>Genetic material wrapped by a protein capsule</p> Signup and view all the answers

    What is the function of the plasma membrane in a cell?

    <p>It is selectively permeable</p> Signup and view all the answers

    What is the fluid mosaic model of the plasma membrane?

    <p>A fluid structure of proteins and phospholipids</p> Signup and view all the answers

    What is the thickness of the plasma membrane?

    <p>Less than 1/10,000 mm</p> Signup and view all the answers

    What is the term for the living substance of a cell?

    <p>Protoplasm</p> Signup and view all the answers

    What is the main component of the plasma membrane?

    <p>Proteins and phospholipids</p> Signup and view all the answers

    What is the function of the nucleus in a cell?

    <p>It contains the genetic material</p> Signup and view all the answers

    What is the function of the protein molecules in the membrane?

    <p>To act as hydrophilic pores, allowing water-soluble chemicals to pass through</p> Signup and view all the answers

    What is the direction of movement of substances during diffusion?

    <p>From higher concentration to lower concentration</p> Signup and view all the answers

    What is the term for the net diffusion of water across a selectively permeable membrane?

    <p>Osmosis</p> Signup and view all the answers

    What is the result of osmosis in a cell?

    <p>Turgor pressure increases</p> Signup and view all the answers

    What type of molecules can dissolve in lipids and cross a cell surface membrane without going through pores?

    <p>Non-polar molecules such as vitamins A, D, E, and K</p> Signup and view all the answers

    What is the type of transport that does not require energy to move substances across a cell membrane?

    <p>Passive transport</p> Signup and view all the answers

    What is the function of the polysaccharides attached to the membrane proteins or lipids?

    <p>To recognize and interact with other cells</p> Signup and view all the answers

    What is the term for the movement of substances from their higher concentration to their lower concentration?

    <p>Diffusion</p> Signup and view all the answers

    What is the type of membrane transport that requires energy to move substances across a cell membrane?

    <p>Active transport</p> Signup and view all the answers

    What is the result of endosmosis in a cell?

    <p>The cell swells</p> Signup and view all the answers

    What is the function of protein molecules in the cell membrane?

    <p>To form hydrophilic pores that allow water-soluble chemicals to pass through</p> Signup and view all the answers

    What is the direction of movement of substances in diffusion?

    <p>From higher concentration to lower concentration</p> Signup and view all the answers

    What is osmosis?

    <p>The net diffusion of water across a selectively permeable membrane</p> Signup and view all the answers

    What is the result of osmosis in a cell?

    <p>The cell experiences turgor pressure</p> Signup and view all the answers

    Which type of molecules can dissolve in lipids?

    <p>Non-polar molecules</p> Signup and view all the answers

    What is the function of polysaccharides attached to membrane proteins or lipids?

    <p>To recognize cells during fertilization</p> Signup and view all the answers

    What is the term for the movement of substances from an area of higher concentration to an area of lower concentration?

    <p>Diffusion</p> Signup and view all the answers

    What is the type of transport that does not require energy to move substances across the cell membrane?

    <p>Passive transport</p> Signup and view all the answers

    What is the result of endosmosis?

    <p>Water enters the cell</p> Signup and view all the answers

    What is the function of the lipid bilayer?

    <p>To act as a barrier to water and water-soluble substances</p> Signup and view all the answers

    What happens to a cell when it is placed in a hypotonic solution?

    <p>The cell increases in size</p> Signup and view all the answers

    What is the primary function of active transport?

    <p>To move substances into the cell</p> Signup and view all the answers

    What type of membrane allows only the solvent to pass through?

    <p>Semipermeable</p> Signup and view all the answers

    What is the main function of the cell wall?

    <p>To provide mechanical strength</p> Signup and view all the answers

    What is the composition of the cell wall in plants?

    <p>Carbohydrate</p> Signup and view all the answers

    What happens to a cell when it is placed in a hypertonic solution?

    <p>The cell decreases in size</p> Signup and view all the answers

    What is the energy source for active transport?

    <p>Adenosine triphosphate (ATP)</p> Signup and view all the answers

    What is the function of transport proteins in active transport?

    <p>To move substances into the cell</p> Signup and view all the answers

    What is the type of solution in which there is no net movement of water molecules?

    <p>Isotonic</p> Signup and view all the answers

    What is the middle lamella composed of?

    <p>Calcium and magnesium pectate</p> Signup and view all the answers

    What is the main component of the cell wall in fungi?

    <p>Chitin</p> Signup and view all the answers

    What is the term for the process in which the protoplasm of a plant cell separates from the cell wall?

    <p>Plasmolysis</p> Signup and view all the answers

    What is the outermost layer of a bacterial cell wall composed of?

    <p>Peptidoglycan</p> Signup and view all the answers

    What is the fluid content of the cell inner to the plasma membrane and excluding the nucleus called?

    <p>Cytoplasm</p> Signup and view all the answers

    What is the function of cell organelles in eukaryotic cells?

    <p>To localize certain cellular processes</p> Signup and view all the answers

    What is the term for the outer protective layer of a bacterial cell?

    <p>Glycocalyx</p> Signup and view all the answers

    What is the composition of the primary cell wall in plant cells?

    <p>Cellulose and pectin</p> Signup and view all the answers

    What is the term for the process of water moving out of a cell?

    <p>Exosmosis</p> Signup and view all the answers

    What is the function of the cytosol in a cell?

    <p>To form the ground substance inside the cell</p> Signup and view all the answers

    What is the term for the thick, tough covering found on some bacterial cells?

    <p>Capsule</p> Signup and view all the answers

    What would happen to a cell when placed in an isotonic solution?

    <p>No net movement of water molecules would occur</p> Signup and view all the answers

    What is the direction of water flow in a hypotonic solution?

    <p>Into the cell</p> Signup and view all the answers

    What process requires energy to move substances across the cell membrane?

    <p>Active transport</p> Signup and view all the answers

    What is the main component of the cell wall in fungi?

    <p>Chitin</p> Signup and view all the answers

    What is the term for the process of the protoplasm separating from the cell wall?

    <p>Plasmolysis</p> Signup and view all the answers

    What is the function of transport proteins in active transport?

    <p>To act as carrier molecules</p> Signup and view all the answers

    What type of membrane allows solvent and selected solutes to pass through?

    <p>Selectively permeable</p> Signup and view all the answers

    What is the function of the glycocalyx in some bacteria?

    <p>Protection from the environment</p> Signup and view all the answers

    What is the function of the cell wall in plant cells?

    <p>To provide mechanical strength</p> Signup and view all the answers

    What is the term for the fluid content of the cell, excluding the nucleus?

    <p>Cytoplasm</p> Signup and view all the answers

    What is the composition of the cell wall in plant cells?

    <p>Carbohydrate</p> Signup and view all the answers

    What is the main component of the cell wall in eubacteria and cyanobacteria?

    <p>Peptidoglycan</p> Signup and view all the answers

    What is the middle lamella composed of in plant cells?

    <p>Calcium and magnesium pectate</p> Signup and view all the answers

    What is the term for the jelly-like substance inside the cell membrane?

    <p>Cytosol</p> Signup and view all the answers

    What is the purpose of the primary wall in plant cells?

    <p>To provide an elastic, thin layer</p> Signup and view all the answers

    What is the term for small, membrane-bound structures within the cell?

    <p>Organelles</p> Signup and view all the answers

    What is the function of exosmosis in cells?

    <p>To remove water from the cell</p> Signup and view all the answers

    What is the term for the process of water leaving the cell, resulting in the protoplasm separating from the cell wall?

    <p>Exosmosis</p> Signup and view all the answers

    What is the function of the slime layer in some bacteria?

    <p>Protection from the environment</p> Signup and view all the answers

    What is the term for the outermost layer of the cell?

    <p>Plasma membrane</p> Signup and view all the answers

    What is the main function of lysosomes in a cell?

    <p>Intracellular digestion</p> Signup and view all the answers

    What is the name given to the process by which lysosomes break down and recycle old or damaged cellular components?

    <p>Autophagy</p> Signup and view all the answers

    What is the shape of lysosomes?

    <p>Polymorphic</p> Signup and view all the answers

    What is the role of lysosomes in the digestion of microorganisms that enter the cell?

    <p>To digest microorganisms</p> Signup and view all the answers

    Why are lysosomes sometimes called 'suicide bags'?

    <p>Because they can digest the whole cell if they burst</p> Signup and view all the answers

    What is the name given to the convex side of the Golgi apparatus that lies towards the nucleus?

    <p>Cis face</p> Signup and view all the answers

    What is the result of autolysis in old cells?

    <p>Cell removal</p> Signup and view all the answers

    What is the function of lysosomes in the gradual disappearance of the tail in a tadpole during metamorphosis?

    <p>To digest tissues</p> Signup and view all the answers

    What is the name of the scientist who first reported lysosomes in 1955?

    <p>Christian de Duve</p> Signup and view all the answers

    In which type of cells are lysosomes typically absent?

    <p>Prokaryotes</p> Signup and view all the answers

    What is the name given to ribosomes due to their function?

    <p>Protein factory of the cell</p> Signup and view all the answers

    What is the composition of ribosomes?

    <p>r-RNA and proteins</p> Signup and view all the answers

    What is the name of the type of ribosomes found in mitochondrial matrix?

    <p>55S</p> Signup and view all the answers

    What is the name of the organelle that is a three-dimensional complicated and interconnecting system of membrane-lined channels?

    <p>Endoplasmic reticulum</p> Signup and view all the answers

    What is the function of smooth ER?

    <p>Glycogen, fat, and steroid synthesis, and detoxification of drugs and poisons</p> Signup and view all the answers

    What is the function of rough ER?

    <p>Protein synthesis</p> Signup and view all the answers

    Who discovered the Golgi apparatus?

    <p>Camillo Golgi</p> Signup and view all the answers

    What is the structure of the Golgi body?

    <p>Single membrane bound</p> Signup and view all the answers

    What is the function of the Golgi body in cell plate formation?

    <p>Secretion of cell plate</p> Signup and view all the answers

    What is the shape of the cisternae in the Golgi body?

    <p>Shallow bowl-like</p> Signup and view all the answers

    What is the term given to ribosomes because of their unique structure?

    <p>organelle within an organelle</p> Signup and view all the answers

    What is the function of smooth endoplasmic reticulum (SER)?

    <p>glycogen and fat synthesis</p> Signup and view all the answers

    What are the two subunits of ribosomes in eukaryotes?

    <p>40S and 60S</p> Signup and view all the answers

    Who discovered the Golgi apparatus?

    <p>Camillo Golgi</p> Signup and view all the answers

    What is the function of the Golgi body?

    <p>secretion and formation of carbohydrates</p> Signup and view all the answers

    What is the term for a cluster of ribosomes attached to messenger RNA?

    <p>polyribosome</p> Signup and view all the answers

    What is the function of rough endoplasmic reticulum (RER)?

    <p>protein synthesis</p> Signup and view all the answers

    What is the type of ribosome found in the mitochondrial matrix of mammals?

    <p>55S</p> Signup and view all the answers

    What is the shape of the cisternae in the Golgi body?

    <p>shallow bowl-like</p> Signup and view all the answers

    What is the function of endoplasmic reticulum (ER)?

    <p>transportation and synthesis of proteins and lipids</p> Signup and view all the answers

    What is the direction of the concave side of the lysosome?

    <p>Towards the plasma membrane</p> Signup and view all the answers

    When were lysosomes first reported?

    <p>1955</p> Signup and view all the answers

    What is the function of lysosomes?

    <p>To perform intracellular digestion</p> Signup and view all the answers

    What is the term for the process of lysosomes digesting old or dead cell organelles?

    <p>Autophagy</p> Signup and view all the answers

    What is the result of lysosomes bursting in a cell?

    <p>The cell's contents are digested</p> Signup and view all the answers

    What is the role of lysosomes in the removal of old cells?

    <p>They release enzymes to break down old cells</p> Signup and view all the answers

    What is the significance of lysosomes in the metamorphosis of tadpoles?

    <p>They help to break down old tissues</p> Signup and view all the answers

    What is the shape of lysosomes?

    <p>Polymorphic</p> Signup and view all the answers

    What is the function of the digestive enzymes in lysosomes?

    <p>To break down waste and foreign materials</p> Signup and view all the answers

    What is the term for the type of lysosome that engulfs bits of cytosol containing waste?

    <p>Autophagic vacuole</p> Signup and view all the answers

    What is the name given to mitochondria due to its role in energy production?

    <p>Powerhouse of the cell</p> Signup and view all the answers

    What is the function of cristae in mitochondria?

    <p>To increase surface area for energy production</p> Signup and view all the answers

    What is the name given to the small tennis racket-like particles on cristae?

    <p>All of the above</p> Signup and view all the answers

    What would happen to a cell if mitochondria were absent?

    <p>Energy metabolism would decrease</p> Signup and view all the answers

    What is the name given to the fluid-filled central cavity of mitochondria?

    <p>Matrix</p> Signup and view all the answers

    What is the function of ATP synthetase enzyme?

    <p>To synthesize ATP</p> Signup and view all the answers

    What is the type of plastid that is colorless?

    <p>Leucoplast</p> Signup and view all the answers

    What is the function of thylakoids in chloroplasts?

    <p>To participate in photosynthesis</p> Signup and view all the answers

    What is the term used to describe the study of the structure and function of organelles?

    <p>Cytology</p> Signup and view all the answers

    What is the term used to describe a membrane-bound, non-cytoplasmic sac?

    <p>Vacuole</p> Signup and view all the answers

    What is the primary function of mitochondria in a cell?

    <p>Energy metabolism</p> Signup and view all the answers

    What is the characteristic feature of the inner membrane of mitochondria?

    <p>It is infolded into the matrix</p> Signup and view all the answers

    What is the role of ATP synthetase enzyme in mitochondria?

    <p>It synthesizes ATP</p> Signup and view all the answers

    What would happen to a cell in the absence of mitochondria?

    <p>Energy metabolism would decrease</p> Signup and view all the answers

    What type of plastid is involved in the synthesis of organic food?

    <p>Chloroplast</p> Signup and view all the answers

    What is the function of thylakoids in chloroplasts?

    <p>Photosynthesis</p> Signup and view all the answers

    What is the main characteristic of vacuoles?

    <p>They are membrane-bound non-cytoplasmic sacs that contain non-living liquid or solid contents</p> Signup and view all the answers

    What is the name of the fluid-filled central cavity surrounded by the inner membrane of mitochondria?

    <p>Matrix</p> Signup and view all the answers

    What type of plastid is colorless and used to store proteins, oil, and starch?

    <p>Leucoplast</p> Signup and view all the answers

    What is the function of cristae in mitochondria?

    <p>To increase the surface area</p> Signup and view all the answers

    What is the primary function of glyoxysomes in plant cells?

    <p>To convert fats into carbohydrates</p> Signup and view all the answers

    What is the characteristic feature of sphaerosomes?

    <p>They are bounded by a single membrane and have lysosome-like activity</p> Signup and view all the answers

    What is the primary function of peroxisomes in animal cells?

    <p>To metabolize peroxides</p> Signup and view all the answers

    What is the role of catalase in peroxisomes?

    <p>To degrade peroxides into water and oxygen</p> Signup and view all the answers

    What is the main function of the cytoskeleton in a cell?

    <p>To provide mechanical support and maintain cell shape</p> Signup and view all the answers

    What is the composition of microtubules?

    <p>Tubulin</p> Signup and view all the answers

    What is the function of microfilaments?

    <p>To be involved in muscle contraction</p> Signup and view all the answers

    What is the characteristic feature of intermediate filaments?

    <p>They have a size/diameter in between microfilaments and microtubules</p> Signup and view all the answers

    What is the role of peroxisomes in plant cells?

    <p>To be involved in photorespiration</p> Signup and view all the answers

    What is the purpose of microtubules during cell division?

    <p>To form spindle fibers</p> Signup and view all the answers

    What is the primary function of glyoxysomes in plant cells?

    <p>Conversion of fats into carbohydrates</p> Signup and view all the answers

    What type of organelles are sphaerosomes similar to?

    <p>Lysosomes</p> Signup and view all the answers

    What is the main function of peroxisomes in animal cells?

    <p>H2O2 metabolism</p> Signup and view all the answers

    What is the primary function of the cytoskeleton in a cell?

    <p>Mechanical support and motility</p> Signup and view all the answers

    What is the composition of microtubules?

    <p>Tubulin</p> Signup and view all the answers

    What is the function of microtubules in plant cells?

    <p>Transport of cell wall material</p> Signup and view all the answers

    What is the composition of microfilaments?

    <p>Actin</p> Signup and view all the answers

    What is the diameter of intermediate filaments relative to microfilaments and microtubules?

    <p>Between microfilaments and microtubules</p> Signup and view all the answers

    What is the function of peroxisomes in plant cells?

    <p>Photorespiration</p> Signup and view all the answers

    What is the function of catalase in peroxisomes?

    <p>Degradates H2O2 into water and oxygen</p> Signup and view all the answers

    What is the function of centrioles during cell division?

    <p>To organise the spindle fibres</p> Signup and view all the answers

    What is the primary function of cilia?

    <p>Causes movement of the cell or surrounding fluid</p> Signup and view all the answers

    What are nucleic acids composed of?

    <p>Nucleotides</p> Signup and view all the answers

    What is unique about the structure of flagella in prokaryotic bacteria?

    <p>They have a different structure than eukaryotic flagella</p> Signup and view all the answers

    What is the function of a nitrogen base in a nucleotide?

    <p>To store genetic information</p> Signup and view all the answers

    What is the difference between ribose and deoxyribose?

    <p>One is found in DNA, the other in RNA</p> Signup and view all the answers

    How do cilia beat?

    <p>In a coordinated manner</p> Signup and view all the answers

    What is a nucleoside composed of?

    <p>A nitrogen base and a pentose sugar</p> Signup and view all the answers

    What is the function of centrioles?

    <p>Not specified in the text</p> Signup and view all the answers

    What are the two types of nitrogen bases found in nucleotides?

    <p>Purines and pyrimidines</p> Signup and view all the answers

    What is the pattern of microtubule triplets in a centriole?

    <p>9 + 0</p> Signup and view all the answers

    Where are centrioles typically found in an animal cell?

    <p>Near the nucleus</p> Signup and view all the answers

    What is the function of phosphoric acid in a nucleotide?

    <p>To form a phosphodiester bond</p> Signup and view all the answers

    In which type of cells are centrioles absent?

    <p>All of the above</p> Signup and view all the answers

    What is the function of centrioles during cell division?

    <p>To organise spindle fibres</p> Signup and view all the answers

    What are nucleic acids composed of?

    <p>Pentose sugar, phosphoric acid, and nitrogen base</p> Signup and view all the answers

    What is a nucleotide?

    <p>A condensation product of three chemicals</p> Signup and view all the answers

    What are the two types of pentose sugars that occur in nucleotides?

    <p>Ribose and deoxyribose</p> Signup and view all the answers

    What is the main function of cilia in a cell?

    <p>To cause movement of the cell or surrounding fluid</p> Signup and view all the answers

    What is the structural difference between prokaryotic and eukaryotic flagella?

    <p>Prokaryotic flagella are structurally different</p> Signup and view all the answers

    What are nitrogen bases classified into?

    <p>Purines and pyrimidines</p> Signup and view all the answers

    What is a combination of a nitrogen base with a pentose sugar known as?

    <p>Nucleoside</p> Signup and view all the answers

    What is the arrangement of microtubules in a centriole?

    <p>9 + 0 pattern of microtubule triplets</p> Signup and view all the answers

    What are the two types of nucleic acids?

    <p>Deoxyribonucleic acid and ribonucleic acid</p> Signup and view all the answers

    Where are centrioles typically located in an animal cell?

    <p>Near the nucleus at right angles to each other</p> Signup and view all the answers

    What is the term for the region surrounding the pair of centrioles?

    <p>Centrosphere</p> Signup and view all the answers

    What is the main difference between cilia and flagella?

    <p>Flagella are longer than cilia</p> Signup and view all the answers

    In which type of cells are centrioles absent?

    <p>All of the above</p> Signup and view all the answers

    What is the primary function of cilia?

    <p>Movement of cell or surrounding fluid</p> Signup and view all the answers

    How do flagella beat?

    <p>Independently in a non-coordinated manner</p> Signup and view all the answers

    What is the structure of centrioles?

    <p>A short cylinder with a 9 + 0 pattern of microtubule triplets</p> Signup and view all the answers

    What is the region surrounding the pair of centrioles called?

    <p>Centrosphere</p> Signup and view all the answers

    In which type of cells are centrioles absent?

    <p>Mature mammalian RBCs</p> Signup and view all the answers

    What is the function of flagella?

    <p>Involved only in locomotion</p> Signup and view all the answers

    How many sets of peripheral triplets do centrioles have?

    <p>9 sets</p> Signup and view all the answers

    What is the purpose of centrioles during cell division?

    <p>To organise the spindle fibres</p> Signup and view all the answers

    What is the name of the sugar found in DNA?

    <p>Deoxyribose</p> Signup and view all the answers

    What is the term for a combination of a nitrogen base with a pentose sugar?

    <p>Nucleoside</p> Signup and view all the answers

    What is the name of the type of nitrogen base that includes adenine and guanine?

    <p>Purine</p> Signup and view all the answers

    What is the name of the type of nitrogen base that includes cytosine and thymine?

    <p>Pyrimidine</p> Signup and view all the answers

    What is the term for the basic units of nucleic acids?

    <p>Nucleotides</p> Signup and view all the answers

    What is the term for the long chain macromolecules that include DNA and RNA?

    <p>Nucleic acids</p> Signup and view all the answers

    What is the shape of the DNA molecule?

    <p>Double helical staircase</p> Signup and view all the answers

    What type of bond holds the two polynucleotide chains of DNA together?

    <p>Weak hydrogen bonds</p> Signup and view all the answers

    What is the rule established by Chargaff?

    <p>A + G = C + T</p> Signup and view all the answers

    What is the nitrogen base found in RNA instead of thymine?

    <p>Uracil</p> Signup and view all the answers

    What is the sugar found in RNA?

    <p>Ribose</p> Signup and view all the answers

    What is the function of RNA in some viruses?

    <p>To carry genetic information</p> Signup and view all the answers

    What is the shape of DNA found in mitochondria, plastids, and prokaryotes?

    <p>Circular</p> Signup and view all the answers

    What is the width of the DNA molecule?

    <p>20 A</p> Signup and view all the answers

    What is the term for RNA that is not the genetic material?

    <p>Non-genetic RNA</p> Signup and view all the answers

    How many nitrogen base pairs are found in a complete turn of the DNA molecule?

    <p>10</p> Signup and view all the answers

    What is the shape of the DNA molecule?

    <p>Double helical staircase</p> Signup and view all the answers

    What is the rule of base equivalence in DNA?

    <p>A + G = C + T</p> Signup and view all the answers

    What is the nitrogen base found in RNA instead of thymine?

    <p>Uracil</p> Signup and view all the answers

    What is the type of RNA that is the genetic material in some viruses?

    <p>Genetic RNA</p> Signup and view all the answers

    What is the width of the DNA molecule?

    <p>20 A</p> Signup and view all the answers

    What is the number of nitrogen base pairs in a complete turn of DNA?

    <p>10</p> Signup and view all the answers

    What is the shape of DNA found in mitochondria, plastids, and prokaryotes?

    <p>Circular</p> Signup and view all the answers

    What is the purpose of the hydrogen bonds in DNA?

    <p>To hold the two polynucleotide chains together</p> Signup and view all the answers

    What is the type of RNA found in the nucleus and cytoplasm of eukaryotic cells?

    <p>Non-genetic RNA</p> Signup and view all the answers

    What is the sugar molecule found in RNA?

    <p>Ribose</p> Signup and view all the answers

    What is the term for organisms that lack a nuclear membrane and the genetic material lies freely in the form of nucleoid?

    <p>Prokaryotes</p> Signup and view all the answers

    What is the function of nucleopores in the nuclear envelope?

    <p>To allow large macromolecules and ribosomes to pass through</p> Signup and view all the answers

    What is the site for the development of ribosomal RNA's?

    <p>Nucleolus</p> Signup and view all the answers

    What is the function of the nucleus in a cell?

    <p>To control metabolic activities and pass genetic information to daughter cells</p> Signup and view all the answers

    What is the term for cells that have multiple nuclei?

    <p>Multinucleated</p> Signup and view all the answers

    Who discovered the nucleus?

    <p>Robert Brown</p> Signup and view all the answers

    What is the structure that surrounds the nucleus and separates it from the cytoplasm?

    <p>Nuclear envelope</p> Signup and view all the answers

    What is the term for the genetic material in a prokaryote?

    <p>Nucleoid</p> Signup and view all the answers

    What is the function of chromatin?

    <p>To form chromosomes</p> Signup and view all the answers

    What is the purpose of the nucleus in the formation of ribosomes?

    <p>To pass genetic information</p> Signup and view all the answers

    What is the function of telomeres in chromosomes?

    <p>To prevent the adhesion of one chromosome to another</p> Signup and view all the answers

    What is the structure composed of DNA and histone proteins in a nucleosome?

    <p>Nucleosome</p> Signup and view all the answers

    What is the characteristic of a metacentric chromosome?

    <p>Centromere is near the middle</p> Signup and view all the answers

    What is the term for the coiled structure of DNA and histone proteins in a chromatid?

    <p>Chromatin fibre</p> Signup and view all the answers

    What is the function of the kinetochore in a chromatid?

    <p>To attach the microtubules to the centromere</p> Signup and view all the answers

    What is the term for the regions of highly repetitive DNA at the terminal parts of linear chromosomes?

    <p>Telomeres</p> Signup and view all the answers

    What is the characteristic of a submetacentric chromosome?

    <p>One arm is slightly shorter than the other</p> Signup and view all the answers

    What is the function of histone proteins in a nucleosome?

    <p>To coil DNA around them</p> Signup and view all the answers

    What is the characteristic of an acrocentric chromosome?

    <p>One arm is very short and the other is very long</p> Signup and view all the answers

    What is the term for the repeating units of chromatin fibre?

    <p>Nucleosomes</p> Signup and view all the answers

    What is the term for the region of highly repetitive DNA found at the terminal parts of linear chromosomes?

    <p>Telomere</p> Signup and view all the answers

    What is the term for the protein structure located at the centromere of a sister chromatid?

    <p>Kinetochore</p> Signup and view all the answers

    What is the term for the central part of a nucleosome, made up of histone proteins around which DNA is coiled?

    <p>Core</p> Signup and view all the answers

    What type of chromosome has a centromere near the middle, resulting in two arms of almost equal length?

    <p>Metacentric chromosome</p> Signup and view all the answers

    What is the term for the part of the DNA that connects two adjacent nucleosomes?

    <p>Linker DNA</p> Signup and view all the answers

    What is the term for the thread-like DNA-containing structure located in the nucleus of eukaryotic cells?

    <p>Chromosome</p> Signup and view all the answers

    What is the term for the constricted region of a chromosome?

    <p>Centromere</p> Signup and view all the answers

    What is the term for the complex of DNA and histone proteins found in eukaryotic chromosomes?

    <p>DNA-histone complex</p> Signup and view all the answers

    What is the term for the process of coiling a long chromatin fibre to fit inside a short chromatid?

    <p>Chromatin condensation</p> Signup and view all the answers

    What is the term for the type of chromosome with a centromere at the tip, resulting in one arm only?

    <p>Telocentric chromosome</p> Signup and view all the answers

    What is the function of the nucleolus in a cell?

    <p>Forming ribosomes</p> Signup and view all the answers

    What is the term for an organism that lacks a nuclear membrane and has genetic material in the form of a nucleoid?

    <p>Prokaryote</p> Signup and view all the answers

    What is the purpose of the nuclear envelope in a cell?

    <p>To separate the cytoplasm from the nucleus</p> Signup and view all the answers

    What is the term for the network of chromatin fibers in the nucleus?

    <p>Chromatin reticulum</p> Signup and view all the answers

    What is the function of the nucleus in a cell?

    <p>All of the above</p> Signup and view all the answers

    What is the term for a cell that has multiple nuclei?

    <p>Multinucleated</p> Signup and view all the answers

    Who discovered the nucleus?

    <p>Robert Brown</p> Signup and view all the answers

    What is the purpose of the nucleopores in the nuclear envelope?

    <p>To allow large macromolecules to pass through</p> Signup and view all the answers

    What is the function of chromatin in the nucleus?

    <p>To store genetic information</p> Signup and view all the answers

    What is the term for the genetic material that lies freely in the form of a nucleoid in prokaryotes?

    <p>Nucleoid</p> Signup and view all the answers

    What is the main function of the nucleus in a cell?

    <p>To store genetic information</p> Signup and view all the answers

    What type of organisms lack a nuclear membrane?

    <p>Prokaryotes</p> Signup and view all the answers

    What is the function of the nucleolus?

    <p>To develop ribosomal RNA</p> Signup and view all the answers

    What is the term for cells that possess multiple nuclei?

    <p>Multinucleated</p> Signup and view all the answers

    What is the function of the nuclear envelope?

    <p>To separate the cytoplasm from the nucleus</p> Signup and view all the answers

    What is the function of chromatin?

    <p>To store genetic information</p> Signup and view all the answers

    What is the term for cells that possess a single nucleus?

    <p>Uninucleated</p> Signup and view all the answers

    What is the function of nucleopores?

    <p>To allow large macromolecules and ribosomes to pass through</p> Signup and view all the answers

    What is the function of the nucleus in terms of genetic information?

    <p>To store genetic information</p> Signup and view all the answers

    What is the term for the complex of DNA and proteins that make up the chromosomes?

    <p>Chromatin</p> Signup and view all the answers

    What is the structural organization of DNA in eukaryotic chromosomes?

    <p>DNA-histone complex</p> Signup and view all the answers

    What is the function of telomeres in chromosomes?

    <p>To prevent chromosomal fusion</p> Signup and view all the answers

    What is the term for the repeating units of chromatin fiber?

    <p>Nucleosomes</p> Signup and view all the answers

    What is the characteristic of metacentric chromosomes?

    <p>Centromere is near the middle</p> Signup and view all the answers

    What is the term for the specialized protein structure located at the centromere?

    <p>Kinetochore</p> Signup and view all the answers

    What is the term for the part of the DNA that connects two adjacent nucleosomes?

    <p>Linker DNA</p> Signup and view all the answers

    What is the shape of the chromosomes in prokaryotes?

    <p>Ring-shaped</p> Signup and view all the answers

    What is the term for the study of the structure and function of cells?

    <p>Cytology</p> Signup and view all the answers

    Where is DNA located in eukaryotes?

    <p>In both the nucleus and organelles</p> Signup and view all the answers

    What is the term for the constriction point of a chromosome?

    <p>Centromere</p> Signup and view all the answers

    What is the term for the complete set of chromosomes found in a gamete?

    <p>Genome</p> Signup and view all the answers

    How many sets of chromosomes do somatic cells of animals and higher plants generally possess?

    <p>Two</p> Signup and view all the answers

    What is the term for chromosomes that determine the sex of an individual?

    <p>Allosomes</p> Signup and view all the answers

    What is the number of chromosomes found in each body cell of a normal human being?

    <p>46</p> Signup and view all the answers

    What is the term for the condition of having half the number of chromosomes?

    <p>Haploid</p> Signup and view all the answers

    What is the term for the process by which two genetically identical daughter cells are produced?

    <p>Mitosis</p> Signup and view all the answers

    What is the arrangement of genes on a chromosome?

    <p>Linear</p> Signup and view all the answers

    What is the term for each chromosome consisting of a number of genes?

    <p>Chromosome</p> Signup and view all the answers

    What is the purpose of cell division in growth, repair, and reproduction?

    <p>To increase the number of cells</p> Signup and view all the answers

    What is the term for chromosomes that are of the same type, size, morphology, and arrangement of gene loci position?

    <p>Homologous chromosomes</p> Signup and view all the answers

    What is the term used to describe a complete set of chromosomes found in gametes?

    <p>Genome</p> Signup and view all the answers

    How many chromosomes are found in each body cell of a normal human being?

    <p>46</p> Signup and view all the answers

    What determines the sex of an individual in dioecious or unisexual organisms?

    <p>Sex chromosomes</p> Signup and view all the answers

    What is the term used to describe a type of cell division that produces two genetically identical daughter cells?

    <p>Mitosis</p> Signup and view all the answers

    What is the condition called when an individual has half the number of chromosomes?

    <p>Haploid</p> Signup and view all the answers

    What is the term used to describe chromosomes that are not sex chromosomes?

    <p>Autosomes</p> Signup and view all the answers

    What is the purpose of cell division?

    <p>Both A and B</p> Signup and view all the answers

    What is a gene?

    <p>A segment of DNA</p> Signup and view all the answers

    What is the term used to describe the complete set of chromosomes found in somatic cells of animals and higher plants?

    <p>Diploid</p> Signup and view all the answers

    What is the function of each gene on a chromosome?

    <p>To carry a specific function</p> Signup and view all the answers

    What is the term used to describe the complete set of chromosomes found in gametes?

    <p>Genome</p> Signup and view all the answers

    What is the number of chromosomes found in each body cell of a normal human being?

    <p>46</p> Signup and view all the answers

    What is the term used to describe the condition of having half the number of chromosomes?

    <p>Haploid</p> Signup and view all the answers

    What determines the sex of an individual in dioecious or unisexual organisms?

    <p>Allosomes</p> Signup and view all the answers

    What is the term used to describe cells that have two sets of chromosomes?

    <p>Diploid</p> Signup and view all the answers

    What is the purpose of cell division?

    <p>Growth, repair, and reproduction</p> Signup and view all the answers

    What type of cell division produces two genetically identical daughter cells?

    <p>Mitosis</p> Signup and view all the answers

    What is the term used to describe chromosomes that are not sex chromosomes?

    <p>Autosomes</p> Signup and view all the answers

    What is the term used to describe two chromosomes of the same type, size, morphology, and arrangement of gene loci positions?

    <p>Homologous chromosomes</p> Signup and view all the answers

    What is each chromosome composed of?

    <p>A set of genes</p> Signup and view all the answers

    What percentage of a cell's life is spent in interphase?

    <p>More than 90%</p> Signup and view all the answers

    What is the purpose of the mitotic spindle?

    <p>To move chromosomes to opposite poles</p> Signup and view all the answers

    What happens to the nucleolus during prophase?

    <p>It disappears</p> Signup and view all the answers

    What is the shortest phase of mitosis?

    <p>Anaphase</p> Signup and view all the answers

    What is the function of cytokinesis?

    <p>To divide the cell into two daughter cells</p> Signup and view all the answers

    What is the characteristic of chromosomes during metaphase?

    <p>They are lined up in a single file</p> Signup and view all the answers

    What is the result of mitosis and cytokinesis?

    <p>Two identical daughter cells</p> Signup and view all the answers

    What happens to the chromatin during interphase?

    <p>It remains threadlike</p> Signup and view all the answers

    What is the longest phase of mitosis?

    <p>Prophase</p> Signup and view all the answers

    What is the function of centrosomes during mitosis?

    <p>To form the mitotic spindle</p> Signup and view all the answers

    What is the primary reason for a cell to obtain organic and inorganic materials from its environment?

    <p>To generate bioenergy and synthesize macromolecular components</p> Signup and view all the answers

    What happens to the normal equilibrium between cell volume and surface area as a cell grows?

    <p>It gets disturbed</p> Signup and view all the answers

    What determines the ratio of cell volume to membrane size?

    <p>The square of the radius of the cell</p> Signup and view all the answers

    What is the consequence of a cell growing larger than its optimal size?

    <p>It needs to divide to restore equilibrium</p> Signup and view all the answers

    What is the function of the nucleus in controlling cell growth?

    <p>It provides genetic information for biosynthesis</p> Signup and view all the answers

    What is unique about the cells of Paramecium?

    <p>They have multiple nuclei</p> Signup and view all the answers

    What is the significance of the capacity of the nucleus in controlling cell growth?

    <p>It affects the synthesis of macromolecular components</p> Signup and view all the answers

    Why do cells need to divide?

    <p>To maintain equilibrium and survive</p> Signup and view all the answers

    What is the relationship between cell volume and surface area as a cell grows?

    <p>The volume increases faster than the surface area</p> Signup and view all the answers

    What is the result of the ratio of cell volume to surface area becoming too large?

    <p>The cell needs to divide to restore equilibrium</p> Signup and view all the answers

    Why do cells need to grow and divide?

    <p>To maintain homeostasis</p> Signup and view all the answers

    What is the result of an imbalance between cell volume and surface area?

    <p>Cell division</p> Signup and view all the answers

    What is the main factor that limits cell size?

    <p>Ratio of cell volume to surface area</p> Signup and view all the answers

    What is the role of the nucleus in controlling cell growth?

    <p>Providing information for cell functions</p> Signup and view all the answers

    What is the significance of the ratio of cell volume to surface area?

    <p>It limits cell growth</p> Signup and view all the answers

    How do large, metabolically active cells adapt to their size?

    <p>By having multiple nuclei</p> Signup and view all the answers

    Why do cells need to divide and restore equilibrium?

    <p>To maintain cellular homeostasis</p> Signup and view all the answers

    What percentage of a cell's life is spent in interphase?

    <p>More than 90%</p> Signup and view all the answers

    What happens to the surface area of the cell membrane as a cell grows?

    <p>It increases as the square of the radius</p> Signup and view all the answers

    What is the consequence of an imbalance between cell volume and surface area?

    <p>Cell division</p> Signup and view all the answers

    During which phase of mitosis do chromosomes line up in a single file?

    <p>Metaphase</p> Signup and view all the answers

    What is the relationship between cell volume and cell membrane surface area?

    <p>Cell volume increases faster than surface area</p> Signup and view all the answers

    What happens to the nuclear membrane during prophase?

    <p>It disappears</p> Signup and view all the answers

    During cytokinesis, what happens to the cell?

    <p>It divides into two daughter cells</p> Signup and view all the answers

    What is the longest phase of mitosis?

    <p>Prophase</p> Signup and view all the answers

    What happens to the chromosomes during anaphase?

    <p>They separate</p> Signup and view all the answers

    What is the purpose of centrosomes in the cell cycle?

    <p>To form the mitotic spindle</p> Signup and view all the answers

    During which phase of the cell cycle does DNA replication occur?

    <p>S</p> Signup and view all the answers

    What is the result of the process of cytokinesis?

    <p>Two daughter cells</p> Signup and view all the answers

    What is the stage of the cell cycle where the cell continues to grow and prepare for cell division?

    <p>G2</p> Signup and view all the answers

    What is the process by which the cell itself is divided into two daughter cells?

    <p>Cytokinesis</p> Signup and view all the answers

    In what stage of mitosis does cytokinesis start in animal cells?

    <p>Anaphase</p> Signup and view all the answers

    What is the term for the process by which homologous chromosomes separate during meiosis?

    <p>Reduction division</p> Signup and view all the answers

    What is the purpose of mitosis in multicellular organisms?

    <p>Replacement of worn-out and damaged tissue</p> Signup and view all the answers

    In which order does cytokinesis occur in plant cells?

    <p>Centrifugal order</p> Signup and view all the answers

    What is the structure formed during cytokinesis in plant cells?

    <p>Cell plate</p> Signup and view all the answers

    What is the function of actin and myosin proteins during cytokinesis in animal cells?

    <p>Formation of the contractile ring</p> Signup and view all the answers

    What is the term for the condition that arises when karyokinesis is not followed by cytokinesis?

    <p>A multinucleate condition</p> Signup and view all the answers

    What is the primary function of synapsis in meiosis?

    <p>To ensure each daughter cell receives one homologue from each parent</p> Signup and view all the answers

    What is the number of chromosomes in gametes produced by meiosis?

    <p>Haploid</p> Signup and view all the answers

    What is the term for the process of cell division that produces gametes with a haploid number of chromosomes?

    <p>Meiosis</p> Signup and view all the answers

    What is the result of crossing-over during meiosis?

    <p>Increased genetic variation among gametes</p> Signup and view all the answers

    What is the term for the visible manifestations of crossing-over events?

    <p>Chiasmata</p> Signup and view all the answers

    How many phases does meiosis II consist of?

    <p>4 phases</p> Signup and view all the answers

    What is the result of meiosis I?

    <p>Daughter cells with a haploid chromosome number</p> Signup and view all the answers

    What is the primary difference between meiosis I and meiosis II?

    <p>Chromosome number</p> Signup and view all the answers

    What is the term for the pairing of homologous chromosomes during meiosis I?

    <p>Synapsis</p> Signup and view all the answers

    What is the result of independent assortment of chromosomes during meiosis?

    <p>Increased genetic variation</p> Signup and view all the answers

    What is the term for the process of homologous chromatids exchanging genetic material during meiosis?

    <p>Crossing-over</p> Signup and view all the answers

    What is the result of meiosis and fertilization in terms of genetic variation?

    <p>Increased genetic variation</p> Signup and view all the answers

    At what stage of mitosis does cytokinesis begin in animal cells?

    <p>Anaphase</p> Signup and view all the answers

    What is the function of phragmoplast in plant cells?

    <p>Organization of Golgi vesicles</p> Signup and view all the answers

    What is the result of karyokinesis not being followed by cytokinesis?

    <p>Multinucleate condition</p> Signup and view all the answers

    What is the purpose of mitosis in multicellular organisms?

    <p>Replacement of worn-out and damaged tissue</p> Signup and view all the answers

    In what order does cytokinesis occur in plant cells?

    <p>Centrifugal order</p> Signup and view all the answers

    What is the number of chromosomes in gametes produced by meiosis?

    <p>Haploid (23)</p> Signup and view all the answers

    What is the first stage of meiosis?

    <p>Meiosis I</p> Signup and view all the answers

    What is the function of actin and myosin proteins in cytokinesis?

    <p>Constriction and furrow formation</p> Signup and view all the answers

    What is the process by which a cell divides into two daughter cells?

    <p>Cytokinesis</p> Signup and view all the answers

    What is the structure formed by the fusion of Golgi vesicles in plant cells?

    <p>Cell plate</p> Signup and view all the answers

    What is the purpose of synapsis in meiosis?

    <p>To ensure each daughter cell receives one homologue from each parent</p> Signup and view all the answers

    What is the result of crossing-over in meiosis?

    <p>Increased genetic variation</p> Signup and view all the answers

    What is the number of chromosomes in each pole of the cell at the end of meiosis?

    <p>Haploid</p> Signup and view all the answers

    What is the phase of meiosis where synapsis and crossing-over occur?

    <p>Prophase I</p> Signup and view all the answers

    What is the function of the spindle fibers in meiosis?

    <p>To separate homologous chromosomes</p> Signup and view all the answers

    What is the outcome of meiosis II?

    <p>Four genetically identical daughter cells</p> Signup and view all the answers

    What is the purpose of cytokinesis in meiosis?

    <p>To divide the cytoplasm</p> Signup and view all the answers

    What is the result of independent assortment of chromosomes during meiosis?

    <p>Increased genetic variation</p> Signup and view all the answers

    What is the main difference between meiosis I and meiosis II?

    <p>Meiosis I has a longer prophase</p> Signup and view all the answers

    What is the number of phases in meiosis?

    <p>Four</p> Signup and view all the answers

    What is the primary function of mitosis in living organisms?

    <p>To repair damaged tissues by producing identical copies of cells</p> Signup and view all the answers

    In which stage of mitosis does cytokinesis start in animal cells?

    <p>Late anaphase</p> Signup and view all the answers

    What is the mechanism of cytokinesis in plant cells?

    <p>Cell plate formation</p> Signup and view all the answers

    What is the order of cytokinesis in plant cells?

    <p>Centrifugal</p> Signup and view all the answers

    What is the result of karyokinesis not being followed by cytokinesis?

    <p>Multinucleate condition</p> Signup and view all the answers

    What is the purpose of meiosis I?

    <p>To separate homologous chromosomes</p> Signup and view all the answers

    What is the chromosome number of gametes produced by meiosis?

    <p>Haploid (23)</p> Signup and view all the answers

    What is the structure formed during cytokinesis in animal cells?

    <p>Contractile ring</p> Signup and view all the answers

    What is the role of microtubules and microfilaments in cytokinesis?

    <p>To arrange on the equator to form the midbody</p> Signup and view all the answers

    What is the direction of cytokinesis in animal cells?

    <p>From the outside to the inside</p> Signup and view all the answers

    What is the purpose of synapsis in meiosis I?

    <p>To ensure that each daughter cell receives one homologue from each parent</p> Signup and view all the answers

    What is the result of crossing-over in meiosis?

    <p>Increased genetic variation among gametes</p> Signup and view all the answers

    What is the chromosome number in the daughter cells at the end of meiosis?

    <p>Monoploid (n)</p> Signup and view all the answers

    What is the longest phase of meiosis I?

    <p>Prophase I</p> Signup and view all the answers

    What is the function of spindle fibers in meiosis I?

    <p>To attach to the kinetochore of each pair of homologous chromosomes</p> Signup and view all the answers

    What is the purpose of meiosis II?

    <p>To separate sister chromatids</p> Signup and view all the answers

    What is the result of independent assortment of chromosomes during meiosis?

    <p>Increased genetic variation among gametes</p> Signup and view all the answers

    What is the effect of crossing-over on genetic variation?

    <p>It increases genetic variation among gametes</p> Signup and view all the answers

    What is the purpose of cytokinesis in meiosis?

    <p>To separate the cytoplasm of the daughter cells</p> Signup and view all the answers

    What is the result of random fertilization of an ovum by a sperm?

    <p>Increased genetic variation among offspring</p> Signup and view all the answers

    What is the chance of a gamete receiving a maternal chromosome during meiosis?

    <p>50%</p> Signup and view all the answers

    What is a characteristic of plant cells that is not found in animal cells?

    <p>Rigid cell wall</p> Signup and view all the answers

    What is the typical location of the nucleus in a plant cell?

    <p>Periphery of the cell</p> Signup and view all the answers

    What is the function of crossover during meiosis?

    <p>To combine genes inherited from both parents</p> Signup and view all the answers

    What is the typical location of the nucleus in an animal cell?

    <p>Center of the cell</p> Signup and view all the answers

    What is a characteristic of animal cells that is not found in plant cells?

    <p>Lysosomes</p> Signup and view all the answers

    What is the typical form of reserve food in plant cells?

    <p>Starch and fat</p> Signup and view all the answers

    What is the reason why plant cells do not burst in a hypotonic solution?

    <p>Because of the presence of a rigid cell wall</p> Signup and view all the answers

    What is the typical diameter of a prokaryotic cell?

    <p>0.2-2.0 pm</p> Signup and view all the answers

    What type of ribosomes are found in prokaryotic cells?

    <p>70S type</p> Signup and view all the answers

    What is the composition of the cell wall in prokaryotic cells?

    <p>Peptidoglycan</p> Signup and view all the answers

    What is the organization of DNA in prokaryotic cells?

    <p>Single circular DNA</p> Signup and view all the answers

    What is the typical diameter of a eukaryotic cell?

    <p>10-100 pm</p> Signup and view all the answers

    What type of ribosomes are found in eukaryotic cells?

    <p>80S type</p> Signup and view all the answers

    What is the composition of the cell wall in eukaryotic cells?

    <p>Cellulose or chitin</p> Signup and view all the answers

    What is the organization of DNA in eukaryotic cells?

    <p>Linear DNA organized into multiple chromosomes</p> Signup and view all the answers

    What is the characteristic of the nucleus in eukaryotic cells?

    <p>True nucleus, consisting of nuclear membrane and nucleoli</p> Signup and view all the answers

    What is the chance of a particular gamete receiving a maternal chromosome during meiosis?

    <p>50 percent</p> Signup and view all the answers

    What is unique about the Golgi apparatus in plant cells?

    <p>It consists of a number of distinct or unconnected units called dictyosomes</p> Signup and view all the answers

    What is the main difference in the size of plant and animal cells?

    <p>Animal cells are smaller</p> Signup and view all the answers

    What is the function of crossover during meiosis?

    <p>To produce recombinant chromosomes that combine genes from both parents</p> Signup and view all the answers

    What is the characteristic of the cell wall in plant cells?

    <p>Rigid and thin</p> Signup and view all the answers

    What is the difference in the number of vacuoles between plant and animal cells?

    <p>Plant cells have a single large vacuole, while animal cells have multiple small vacuoles</p> Signup and view all the answers

    Why do plant cells not burst when placed in a hypotonic solution?

    <p>Due to the presence of a cell wall</p> Signup and view all the answers

    What is the main difference in the presence of centrioles between plant and animal cells?

    <p>Animal cells have centrioles, while plant cells often lack them</p> Signup and view all the answers

    What is the typical size range of prokaryotic cells?

    <p>0.2-2.0 pm in diameter</p> Signup and view all the answers

    What is the main characteristic of a prokaryotic nucleus?

    <p>It has no nuclear membrane or nucleolus</p> Signup and view all the answers

    What type of ribosomes are found in prokaryotic cells?

    <p>70S type of ribosomes</p> Signup and view all the answers

    What is the characteristic of the cell wall in prokaryotic cells?

    <p>It is made up of peptidoglycan</p> Signup and view all the answers

    What is the characteristic of the DNA in prokaryotic cells?

    <p>It is single and circular</p> Signup and view all the answers

    What is the typical size range of eukaryotic cells?

    <p>10-100 pm in diameter</p> Signup and view all the answers

    What is the main characteristic of a eukaryotic nucleus?

    <p>It has a true nucleus with a nuclear membrane</p> Signup and view all the answers

    What type of ribosomes are found in eukaryotic cells?

    <p>80S type of ribosomes</p> Signup and view all the answers

    What happens to animal cells in a hypotonic solution?

    <p>They burst due to the absence of a cell wall</p> Signup and view all the answers

    What is the chance that a particular gamete will receive a maternal chromosome during meiosis?

    <p>50 percent</p> Signup and view all the answers

    What is a characteristic of a plant cell that is not found in an animal cell?

    <p>Plastids are present</p> Signup and view all the answers

    What is the function of crossover during meiosis?

    <p>To produce recombinant chromosomes that combine genes inherited from both parents</p> Signup and view all the answers

    What is a characteristic of the Golgi apparatus in plant cells?

    <p>It consists of distinct or unconnected units called dictyosomes</p> Signup and view all the answers

    What is the main difference between the shape of plant and animal cells?

    <p>Animal cells can often change their shape</p> Signup and view all the answers

    What is the function of lysosomes in animal cells?

    <p>To perform digestion and recycle cellular waste</p> Signup and view all the answers

    What is the reserve food material found in plant cells?

    <p>Starch or fat</p> Signup and view all the answers

    What is the nucleus location in a plant cell?

    <p>On one side in the peripheral cytoplasm</p> Signup and view all the answers

    What is the typical diameter of prokaryotic cells?

    <p>0.2-2.0 pm</p> Signup and view all the answers

    What is the composition of the cell wall in eukaryotes?

    <p>Chitin or cellulose</p> Signup and view all the answers

    What type of ribosomes do eukaryotic cells have?

    <p>80S type</p> Signup and view all the answers

    What is the characteristic of the nucleus in prokaryotic cells?

    <p>Has no nuclear membrane or nucleoli</p> Signup and view all the answers

    What is the structure of DNA in eukaryotic cells?

    <p>Linear DNA organized into multiple chromosomes</p> Signup and view all the answers

    What is the size range of eukaryotic cells?

    <p>10-100 pm</p> Signup and view all the answers

    What is absent in prokaryotic cells?

    <p>Membrane-enclosed organelles</p> Signup and view all the answers

    What is the difference in cell wall composition between prokaryotic and eukaryotic cells?

    <p>Prokaryotes have peptidoglycan, eukaryotes have cellulose or chitin</p> Signup and view all the answers

    What is a characteristic of eukaryotic cells that is not found in prokaryotic cells?

    <p>True nucleus with nuclear membrane and nucleoli</p> Signup and view all the answers

    Study Notes

    The Fundamental Unit of Life

    • The cell is the basic unit of structure and function in living organisms.

    Cytology

    • Cytology is the branch of biology that deals with the study of structure and function of plant and animal cells.

    Invention of Microscope

    • The simplest microscope was constructed in 1600.
    • Galileo and Anton van Leeuwenhoek later used the microscope.
    • In 1665, Robert Hooke observed a thin slice of cork (dead cell) under the microscope and saw like structures, which he called cells.
    • These "cells" were actually seed cells of the outer cover of the plant called periderm bark.

    Microscope Sections

    • A thin slice of any part is called a section.
    • A longitudinal section is a cut along the length of a structure.
    • A transverse section is a cut across a structure.

    Working of a Microscope

    • A microscope uses light reflected by a mirror, directed through the specimen into the lenses.
    • The lenses produce a greatly magnified image of the specimen, which can be studied directly or photographed.
    • The object is placed on a glass slide on a stage with a central hole under an objective lens.
    • Light is reflected through the specimen with the help of a mirror and condenser below the stage.
    • The magnified image is seen through an eyepiece at the top of the microscope.
    • Focusing is done by adjusting coarse and fine adjustors.
    • Various lenses are available, including:
      • Eyepiece lenses with magnifications of 5X, 10X, and 15X.
      • Objective lenses with magnifications of 40X, 100X (high power), and 10X (low power).

    Magnification

    • Magnification is calculated as observed size divided by actual size.
    • Under a microscope, cells become magnified, making them easier to observe.

    The Fundamental Unit of Life

    • The cell is the basic unit of structure and function in living organisms.

    Cytology

    • Cytology is the branch of biology that deals with the study of structure and function of plant and animal cells.

    Invention of Microscope

    • The simplest microscope was constructed in 1600.
    • Galileo and Anton van Leeuwenhoek later used the microscope.
    • In 1665, Robert Hooke observed a thin slice of cork (dead cell) under the microscope and saw like structures, which he called cells.
    • These "cells" were actually seed cells of the outer cover of the plant called periderm bark.

    Microscope Sections

    • A thin slice of any part is called a section.
    • A longitudinal section is a cut along the length of a structure.
    • A transverse section is a cut across a structure.

    Working of a Microscope

    • A microscope uses light reflected by a mirror, directed through the specimen into the lenses.
    • The lenses produce a greatly magnified image of the specimen, which can be studied directly or photographed.
    • The object is placed on a glass slide on a stage with a central hole under an objective lens.
    • Light is reflected through the specimen with the help of a mirror and condenser below the stage.
    • The magnified image is seen through an eyepiece at the top of the microscope.
    • Focusing is done by adjusting coarse and fine adjustors.
    • Various lenses are available, including:
      • Eyepiece lenses with magnifications of 5X, 10X, and 15X.
      • Objective lenses with magnifications of 40X, 100X (high power), and 10X (low power).

    Magnification

    • Magnification is calculated as observed size divided by actual size.
    • Under a microscope, cells become magnified, making them easier to observe.

    The Fundamental Unit of Life

    • The cell is the basic unit of structure and function in living organisms.

    Cytology

    • Cytology is the branch of biology that deals with the study of structure and function of plant and animal cells.

    Invention of Microscope

    • The simplest microscope was constructed in 1600.
    • Galileo and Anton van Leeuwenhoek later used the microscope.
    • In 1665, Robert Hooke observed a thin slice of cork (dead cell) under the microscope and saw like structures, which he called cells.
    • These "cells" were actually seed cells of the outer cover of the plant called periderm bark.

    Microscope Sections

    • A thin slice of any part is called a section.
    • A longitudinal section is a cut along the length of a structure.
    • A transverse section is a cut across a structure.

    Working of a Microscope

    • A microscope uses light reflected by a mirror, directed through the specimen into the lenses.
    • The lenses produce a greatly magnified image of the specimen, which can be studied directly or photographed.
    • The object is placed on a glass slide on a stage with a central hole under an objective lens.
    • Light is reflected through the specimen with the help of a mirror and condenser below the stage.
    • The magnified image is seen through an eyepiece at the top of the microscope.
    • Focusing is done by adjusting coarse and fine adjustors.
    • Various lenses are available, including:
      • Eyepiece lenses with magnifications of 5X, 10X, and 15X.
      • Objective lenses with magnifications of 40X, 100X (high power), and 10X (low power).

    Magnification

    • Magnification is calculated as observed size divided by actual size.
    • Under a microscope, cells become magnified, making them easier to observe.

    Microscope Magnification

    • Light microscopes use 10X or 40X objective lenses and 10X or higher eyepiece lenses, resulting in total magnification ranges of 100X to 450X.
    • The best light microscopes can magnify structures up to 1500 times their original size.

    Cell Theory

    • Formulated by Matthias Schleiden in 1838 and Theodor Schwann in 1839.
    • States that:
      • All living organisms are composed of cells and products of cells.
      • All cells arise from pre-existing cells.

    Cell Characteristics

    • Size: Ranges from 10 to 100 microns; examples include:
      • The ostrich egg, which has the largest animal cell.
      • PPLO (Pleuropneumonia-like organism), which is the smallest cell, measuring 0.1 to 0.5 microns.
    • Shape: Depends on specific cell function; examples include:
      • Elongated and branched: Nerve cells.
      • Discoidal/saucer-shaped: Red blood cells.
      • Spindle-shaped: Muscle cells.
      • Spherical: Eggs.
      • Branched: Pigment cells of the skin.
      • Slipper-shaped: Paramecium.
      • Cuboidal: Germ cells of gonads.
      • Polygonal: Liver cells.

    Microscope Magnification

    • Light microscopes use 10X or 40X objective lenses and 10X or higher eyepiece lenses, resulting in total magnification ranges of 100X to 450X.
    • The best light microscopes can magnify structures up to 1500 times their original size.

    Cell Theory

    • Formulated by Matthias Schleiden in 1838 and Theodor Schwann in 1839.
    • States that:
      • All living organisms are composed of cells and products of cells.
      • All cells arise from pre-existing cells.

    Cell Characteristics

    • Size: Ranges from 10 to 100 microns; examples include:
      • The ostrich egg, which has the largest animal cell.
      • PPLO (Pleuropneumonia-like organism), which is the smallest cell, measuring 0.1 to 0.5 microns.
    • Shape: Depends on specific cell function; examples include:
      • Elongated and branched: Nerve cells.
      • Discoidal/saucer-shaped: Red blood cells.
      • Spindle-shaped: Muscle cells.
      • Spherical: Eggs.
      • Branched: Pigment cells of the skin.
      • Slipper-shaped: Paramecium.
      • Cuboidal: Germ cells of gonads.
      • Polygonal: Liver cells.

    Microscope Magnification

    • Light microscopes use 10X or 40X objective lenses and 10X or higher eyepiece lenses, resulting in total magnification ranges of 100X to 450X.
    • The best light microscopes can magnify structures up to 1500 times their original size.

    Cell Theory

    • Formulated by Matthias Schleiden in 1838 and Theodor Schwann in 1839.
    • States that:
      • All living organisms are composed of cells and products of cells.
      • All cells arise from pre-existing cells.

    Cell Characteristics

    • Size: Ranges from 10 to 100 microns; examples include:
      • The ostrich egg, which has the largest animal cell.
      • PPLO (Pleuropneumonia-like organism), which is the smallest cell, measuring 0.1 to 0.5 microns.
    • Shape: Depends on specific cell function; examples include:
      • Elongated and branched: Nerve cells.
      • Discoidal/saucer-shaped: Red blood cells.
      • Spindle-shaped: Muscle cells.
      • Spherical: Eggs.
      • Branched: Pigment cells of the skin.
      • Slipper-shaped: Paramecium.
      • Cuboidal: Germ cells of gonads.
      • Polygonal: Liver cells.

    Microscope Magnification

    • Light microscopes use 10X or 40X objective lenses and 10X or higher eyepiece lenses, resulting in total magnification ranges of 100X to 450X.
    • The best light microscopes can magnify structures up to 1500 times their original size.

    Cell Theory

    • Formulated by Matthias Schleiden in 1838 and Theodor Schwann in 1839.
    • States that:
      • All living organisms are composed of cells and products of cells.
      • All cells arise from pre-existing cells.

    Cell Characteristics

    • Size: Ranges from 10 to 100 microns; examples include:
      • The ostrich egg, which has the largest animal cell.
      • PPLO (Pleuropneumonia-like organism), which is the smallest cell, measuring 0.1 to 0.5 microns.
    • Shape: Depends on specific cell function; examples include:
      • Elongated and branched: Nerve cells.
      • Discoidal/saucer-shaped: Red blood cells.
      • Spindle-shaped: Muscle cells.
      • Spherical: Eggs.
      • Branched: Pigment cells of the skin.
      • Slipper-shaped: Paramecium.
      • Cuboidal: Germ cells of gonads.
      • Polygonal: Liver cells.

    Unicellular and Multicellular Organisms

    • Unicellular organisms are made up of a single cell, examples include Bacteria, Amoeba, Paramecium, and Chlamydomonas.
    • Multicellular organisms are made up of multiple cells, examples include Fungi (except yeast), plants, and animals.

    Viruses

    • Viruses are the only living beings that do not have cells.
    • Viruses are composed of genetic material (DNA or RNA) wrapped in a protein capsule.

    Cell Organization

    • All cells have three major functional regions: plasma membrane, cytoplasm, and nucleus.
    • Cytoplasm and nucleus together are known as protoplasm.

    Plasma Membrane

    • The plasma membrane is a membrane that bounds all cells, enclosing the protoplasm.
    • Characteristics of the plasma membrane:
    • Made up of proteins and phospholipids
    • Selectively permeable, allowing only specific solutes to pass through
    • Thickness is less than 1/10,000 mm (70A)
    • Best explained by the fluid mosaic model proposed by Singer and Nicolson (1972)
    • Enables functions such as diffusion, osmosis, and ion movement.

    Unicellular and Multicellular Organisms

    • Unicellular organisms are made up of a single cell, examples include Bacteria, Amoeba, Paramecium, and Chlamydomonas.
    • Multicellular organisms are made up of multiple cells, examples include Fungi (except yeast), plants, and animals.

    Viruses

    • Viruses are the only living beings that do not have cells.
    • Viruses are composed of genetic material (DNA or RNA) wrapped in a protein capsule.

    Cell Organization

    • All cells have three major functional regions: plasma membrane, cytoplasm, and nucleus.
    • Cytoplasm and nucleus together are known as protoplasm.

    Plasma Membrane

    • The plasma membrane is a membrane that bounds all cells, enclosing the protoplasm.
    • Characteristics of the plasma membrane:
    • Made up of proteins and phospholipids
    • Selectively permeable, allowing only specific solutes to pass through
    • Thickness is less than 1/10,000 mm (70A)
    • Best explained by the fluid mosaic model proposed by Singer and Nicolson (1972)
    • Enables functions such as diffusion, osmosis, and ion movement.

    Cell Membrane Structure and Function

    • Polysaccharides attached to membrane proteins or lipids are involved in cell-to-cell recognition mechanisms, such as fertilization.
    • The lipid bilayer is a barrier to water and water-soluble substances.
    • Protein molecules in the membrane act as hydrophilic pores, allowing water-soluble chemicals to pass through.
    • Pores are small and highly selective, allowing only specific molecules or ions to pass through.

    Polar and Non-Polar Substances

    • Water is a polar molecule with regions of positive and negative charge, allowing it to dissolve polar substances like sugars, ions (Na+, Cl-, Ca2+, K+), B and C vitamins, and amino acids.
    • Polar substances do not dissolve in lipids and must cross the cell surface membrane through pores.
    • Non-polar molecules like fats, oils, and lipids lack charged regions and do not dissolve in water.
    • Non-polar substances like vitamins A, D, E, and K can dissolve in lipids and cross the cell surface membrane without passing through pores.

    Transport Across the Plasma Membrane

    Passive Transport

    • A type of membrane transport that does not require energy to move substances across the cell membrane.

    Diffusion

    • The movement of substances from higher concentration to lower concentration, such as oxygen diffusing from alveoli into the blood in capillaries.

    Osmosis

    • The net diffusion of water across a selectively permeable membrane towards a higher solute concentration, such as the absorption of water from soil by roots.
    • Osmosis results in hydrostatic pressure within the cell, known as turgor pressure.
    • There are two types of osmosis: endosmosis and exosmosis.

    Cell Membrane Structure and Function

    • Polysaccharides attached to membrane proteins or lipids are involved in cell-to-cell recognition mechanisms, such as fertilization.
    • The lipid bilayer is a barrier to water and water-soluble substances.
    • Protein molecules in the membrane act as hydrophilic pores, allowing water-soluble chemicals to pass through.
    • Pores are small and highly selective, allowing only specific molecules or ions to pass through.

    Polar and Non-Polar Substances

    • Water is a polar molecule with regions of positive and negative charge, allowing it to dissolve polar substances like sugars, ions (Na+, Cl-, Ca2+, K+), B and C vitamins, and amino acids.
    • Polar substances do not dissolve in lipids and must cross the cell surface membrane through pores.
    • Non-polar molecules like fats, oils, and lipids lack charged regions and do not dissolve in water.
    • Non-polar substances like vitamins A, D, E, and K can dissolve in lipids and cross the cell surface membrane without passing through pores.

    Transport Across the Plasma Membrane

    Passive Transport

    • A type of membrane transport that does not require energy to move substances across the cell membrane.

    Diffusion

    • The movement of substances from higher concentration to lower concentration, such as oxygen diffusing from alveoli into the blood in capillaries.

    Osmosis

    • The net diffusion of water across a selectively permeable membrane towards a higher solute concentration, such as the absorption of water from soil by roots.
    • Osmosis results in hydrostatic pressure within the cell, known as turgor pressure.
    • There are two types of osmosis: endosmosis and exosmosis.

    Osmosis and Cell Response

    • When a cell is placed in an isotonic solution, there is no net movement of water molecules, and the cell size remains the same.
    • In a hypotonic solution, water molecules flow into the cell, causing the cell to swell, a process known as endosmosis.
    • In a hypertonic solution, water molecules flow out of the cell, causing the cell to shrink, a process known as exosmosis.

    Active Transport

    • Active transport is the movement of substances through the cell membrane that requires energy, provided by adenosine triphosphate (ATP) produced by aerobic respiration in the mitochondria.
    • This process is rapid, unidirectional, and involves transport proteins that help move substances into and out of the cell.

    Cell Membrane Permeability

    • Cell membranes can be permeable (allowing solvents and solutes to pass), semipermeable (only allowing solvents to pass), selectively permeable (allowing solvents and selected solutes to pass), or impermeable (not allowing anything to pass).

    Cell Wall

    • The cell wall is an additional protective covering outside the cell membrane, found in plants, fungi, bacterial cells, and certain protists.
    • It provides mechanical strength, shape, and rigidity to the cell.
    • In plants, the cell wall is made up of cellulose, a type of carbohydrate.
    • The cell wall consists of three layers: middle lamella (cementing layer), primary wall (thinner, elastic layer), and secondary wall (thicker layer in mature, non-dividing cells).

    Cell Organelles

    • Cytoplasm is the fluid content/protoplasmic mass of the cell, excluding the nucleus, and consists of cytosol (aqueous, transparent, structureless ground substance) and cell organelles (subcellular structures with characteristic form, structure, and function).

    Plasmolysis

    • When a plant cell is placed in a hypertonic solution, exosmosis occurs from the central vacuole, causing the protoplasm to separate from the cell wall, a process known as plasmolysis.

    Osmosis and Cell Response

    • When a cell is placed in an isotonic solution, there is no net movement of water molecules, and the cell size remains the same.
    • In a hypotonic solution, water molecules flow into the cell, causing the cell to swell, a process known as endosmosis.
    • In a hypertonic solution, water molecules flow out of the cell, causing the cell to shrink, a process known as exosmosis.

    Active Transport

    • Active transport is the movement of substances through the cell membrane that requires energy, provided by adenosine triphosphate (ATP) produced by aerobic respiration in the mitochondria.
    • This process is rapid, unidirectional, and involves transport proteins that help move substances into and out of the cell.

    Cell Membrane Permeability

    • Cell membranes can be permeable (allowing solvents and solutes to pass), semipermeable (only allowing solvents to pass), selectively permeable (allowing solvents and selected solutes to pass), or impermeable (not allowing anything to pass).

    Cell Wall

    • The cell wall is an additional protective covering outside the cell membrane, found in plants, fungi, bacterial cells, and certain protists.
    • It provides mechanical strength, shape, and rigidity to the cell.
    • In plants, the cell wall is made up of cellulose, a type of carbohydrate.
    • The cell wall consists of three layers: middle lamella (cementing layer), primary wall (thinner, elastic layer), and secondary wall (thicker layer in mature, non-dividing cells).

    Cell Organelles

    • Cytoplasm is the fluid content/protoplasmic mass of the cell, excluding the nucleus, and consists of cytosol (aqueous, transparent, structureless ground substance) and cell organelles (subcellular structures with characteristic form, structure, and function).

    Plasmolysis

    • When a plant cell is placed in a hypertonic solution, exosmosis occurs from the central vacuole, causing the protoplasm to separate from the cell wall, a process known as plasmolysis.

    Ribosomes

    • Ribosomes are also called "organelle within an organelle" and the protein factory of the cell
    • Each ribosome is made up of two unequal subunits that join together during protein synthesis in the presence of Mg2+ ions
    • Ribosomes are small, sub-spherical, granular organelles not enclosed by a membrane
    • They are composed of r-RNA and proteins and attach to m-RNA to form polyribosomes during protein synthesis
    • In prokaryotes, the two subunits are 30S and 50S (together 70S), and in eukaryotes, they are 40S and 60S (together 80S)
    • In mammals, 55S type of ribosomes are present in the mitochondrial matrix

    Endoplasmic Reticulum (ER)

    • ER is a three-dimensional, complicated, interconnecting system of membrane-lined channels that run through the cytoplasm
    • ER remains continuous with the plasma membrane, nuclear envelope, and Golgi body
    • ER is composed of cisternae, vesicles, and tubules
    • There are two types of ER: smooth ER and rough ER
    • Smooth ER is engaged in the synthesis and storage of glycogen, fat, and steroids, and detoxification of drugs and poisons
    • Rough ER is associated with protein synthesis due to the presence of ribosomes on its surface

    Golgi Body

    • The Golgi body was discovered by Camillo Golgi in 1898 in nerve cells of owls and cats
    • In animal cells, it is localized near the nucleus, but in plant cells, it is in the form of unconnected units called dictyosomes
    • The Golgi body is composed of cisternae, vesicles, tubules, and vacuoles
    • It is a single membrane-bound organelle
    • Functions of the Golgi body include secretion, formation of carbohydrates, glycoproteins, cell wall, cell membrane, lysosomes, acrosome of sperm, and cell plate formation

    Lysosomes

    • Lysosomes were first reported by Christian de Duve in 1955
    • They occur in most animal cells but are absent in prokaryotes
    • Lysosomes are tiny, membrane-bound, vesicular structures that perform intracellular digestion
    • They are polymorphic, with four types: primary lysosomes, secondary lysosomes, residual bodies, and autophagic vacuoles
    • Lysosomes regularly engulf bits of cytosol containing waste, foreign material, and worn-out cell organelles, which are digested there
    • They contain digestive enzymes capable of digesting proteins, carbohydrates, lipids, and nucleic acids
    • Lysosomes are involved in the digestion of microorganisms such as bacteria entering the cell by phagocytosis
    • In certain conditions, lysosomes start to digest old or dead cell organelles, a process known as autophagy
    • Lysosomes are sometimes called "suicide bags" because the enzymes they contain could digest the whole cell if they burst

    Ribosomes

    • Ribosomes are also called "organelle within an organelle" and the protein factory of the cell
    • Each ribosome is made up of two unequal subunits that join together during protein synthesis in the presence of Mg2+ ions
    • Ribosomes are small, sub-spherical, granular organelles not enclosed by a membrane
    • They are composed of r-RNA and proteins and attach to m-RNA to form polyribosomes during protein synthesis
    • In prokaryotes, the two subunits are 30S and 50S (together 70S), and in eukaryotes, they are 40S and 60S (together 80S)
    • In mammals, 55S type of ribosomes are present in the mitochondrial matrix

    Endoplasmic Reticulum (ER)

    • ER is a three-dimensional, complicated, interconnecting system of membrane-lined channels that run through the cytoplasm
    • ER remains continuous with the plasma membrane, nuclear envelope, and Golgi body
    • ER is composed of cisternae, vesicles, and tubules
    • There are two types of ER: smooth ER and rough ER
    • Smooth ER is engaged in the synthesis and storage of glycogen, fat, and steroids, and detoxification of drugs and poisons
    • Rough ER is associated with protein synthesis due to the presence of ribosomes on its surface

    Golgi Body

    • The Golgi body was discovered by Camillo Golgi in 1898 in nerve cells of owls and cats
    • In animal cells, it is localized near the nucleus, but in plant cells, it is in the form of unconnected units called dictyosomes
    • The Golgi body is composed of cisternae, vesicles, tubules, and vacuoles
    • It is a single membrane-bound organelle
    • Functions of the Golgi body include secretion, formation of carbohydrates, glycoproteins, cell wall, cell membrane, lysosomes, acrosome of sperm, and cell plate formation

    Lysosomes

    • Lysosomes were first reported by Christian de Duve in 1955
    • They occur in most animal cells but are absent in prokaryotes
    • Lysosomes are tiny, membrane-bound, vesicular structures that perform intracellular digestion
    • They are polymorphic, with four types: primary lysosomes, secondary lysosomes, residual bodies, and autophagic vacuoles
    • Lysosomes regularly engulf bits of cytosol containing waste, foreign material, and worn-out cell organelles, which are digested there
    • They contain digestive enzymes capable of digesting proteins, carbohydrates, lipids, and nucleic acids
    • Lysosomes are involved in the digestion of microorganisms such as bacteria entering the cell by phagocytosis
    • In certain conditions, lysosomes start to digest old or dead cell organelles, a process known as autophagy
    • Lysosomes are sometimes called "suicide bags" because the enzymes they contain could digest the whole cell if they burst

    Mitochondria

    • Mitochondria are known as the powerhouse of the cell or ATP generation site.
    • They are enclosed in a double membrane envelop, with a smooth outer membrane and an inner membrane that surrounds a fluid-filled central cavity called the matrix.
    • The inner membrane is infolded into the matrix as incomplete partitions called cristae, which increase the surface area.
    • Cristae bear small tennis racket-like particles called elementary particles, Fo-F1 particles, or oxysomes, which are associated with respiration and the formation of energy in the form of ATP.
    • Mitochondria have their own DNA and ribosome and can self-replicate, making them semi-autonomous bodies.
    • ATP synthetase enzyme is responsible for the formation of ATP.
    • In the absence of mitochondria, a cell's energy metabolism would be severely reduced.

    Plastids

    • Plastids are semi-autonomous organelles with DNA and a double membrane envelope.
    • There are three types of plastids: leucoplasts, chromoplasts, and chloroplasts.
    • Leucoplasts are colorless and used to store proteins, oil, and starch.
    • Chromoplasts are colored and contain pigments other than green.
    • Chloroplasts are green and participate in the synthesis of organic food through photosynthesis.
    • Chloroplasts have a ground substance called stroma, with membranous structures called thylakoids that contain chlorophyll and are arranged in stacks to form grana.
    • The main functions of plastids are photosynthesis, storage of fats, proteins, and starch.

    Vacuoles

    • Vacuoles are membrane-bound non-cytoplasmic sacs that contain non-living liquid or solid contents.
    • They are common in both plant and animal cells.
    • In animal and young plant cells, sap vacuoles are small.
    • In mature plant cells, there is a large central vacuole that occupies 50-90% of the cell volume.
    • The covering membrane of the vacuole is called tonoplast.
    • The fluid content of the vacuole is called cell sap.
    • Vacuoles store salts, sugars, amino acids, organic acids, and some proteins.
    • They also act as a dump for waste products in plant cells and help maintain turgidity and rigidity of the cell.

    Mitochondria

    • Mitochondria are known as the powerhouse of the cell or ATP generation site.
    • They are enclosed in a double membrane envelop, with a smooth outer membrane and an inner membrane that surrounds a fluid-filled central cavity called the matrix.
    • The inner membrane is infolded into the matrix as incomplete partitions called cristae, which increase the surface area.
    • Cristae bear small tennis racket-like particles called elementary particles, Fo-F1 particles, or oxysomes, which are associated with respiration and the formation of energy in the form of ATP.
    • Mitochondria have their own DNA and ribosome and can self-replicate, making them semi-autonomous bodies.
    • ATP synthetase enzyme is responsible for the formation of ATP.
    • In the absence of mitochondria, a cell's energy metabolism would be severely reduced.

    Plastids

    • Plastids are semi-autonomous organelles with DNA and a double membrane envelope.
    • There are three types of plastids: leucoplasts, chromoplasts, and chloroplasts.
    • Leucoplasts are colorless and used to store proteins, oil, and starch.
    • Chromoplasts are colored and contain pigments other than green.
    • Chloroplasts are green and participate in the synthesis of organic food through photosynthesis.
    • Chloroplasts have a ground substance called stroma, with membranous structures called thylakoids that contain chlorophyll and are arranged in stacks to form grana.
    • The main functions of plastids are photosynthesis, storage of fats, proteins, and starch.

    Vacuoles

    • Vacuoles are membrane-bound non-cytoplasmic sacs that contain non-living liquid or solid contents.
    • They are common in both plant and animal cells.
    • In animal and young plant cells, sap vacuoles are small.
    • In mature plant cells, there is a large central vacuole that occupies 50-90% of the cell volume.
    • The covering membrane of the vacuole is called tonoplast.
    • The fluid content of the vacuole is called cell sap.
    • Vacuoles store salts, sugars, amino acids, organic acids, and some proteins.
    • They also act as a dump for waste products in plant cells and help maintain turgidity and rigidity of the cell.

    Organelles in Plant Cells

    • Glyoxysomes are organelles found only in plant cells, especially in fatty seeds and unripe fruits.
    • They are highly specialized peroxisomes that convert fats into carbohydrates.
    • Glyoxysomes are related to the metabolism of fats.

    Sphaerosomes

    • Sphaerosomes are small, single-membrane organelles found only in plant cells.
    • They are the major site of lipid storage and synthesis in plants.
    • Sphaerosomes also have lysosome-like activity, earning them the term "plant lysosomes".

    Peroxisomes or Uricosomes

    • In animal cells, peroxisomes are involved in peroxide (H2O2) metabolism.
    • They contain enzymes like urate oxidase, amino acid oxidase, and peroxidase.
    • Peroxidase induces the oxidation of amino acids to produce H2O2.
    • Catalase degrades H2O2 into water and oxygen.
    • In plant cells, peroxisomes occur in cells of green tissues and are involved in photorespiration.
    • They also detoxify alcohol in liver cells.

    Cytoskeleton

    • The cytoskeleton is an elaborate network of filamentous proteinaceous structures present in the cytoplasm.
    • It provides mechanical support, motility, and maintains the shape of the cell.
    • The cytoskeleton consists of microtubules, microfilaments, and intermediate filaments.

    Microtubules

    • Microtubules are composed of protein tubulin.
    • In plant cells, microtubules are often found associated with the cell wall.
    • They probably transport cell wall material from the Golgi body to the outside of the cell.
    • During cell division, microtubules form spindle fibers.

    Microfilaments

    • Microfilaments are composed of contractile protein actin.
    • Actin is concerned with muscle contraction.

    Intermediate Filaments

    • Intermediate filaments have a size/diameter between microfilaments and microtubules.
    • They form basket-like structures around the nucleus.

    Organelles in Plant Cells

    • Glyoxysomes are organelles found only in plant cells, especially in fatty seeds and unripe fruits.
    • They are highly specialized peroxisomes that convert fats into carbohydrates.
    • Glyoxysomes are related to the metabolism of fats.

    Sphaerosomes

    • Sphaerosomes are small, single-membrane organelles found only in plant cells.
    • They are the major site of lipid storage and synthesis in plants.
    • Sphaerosomes also have lysosome-like activity, earning them the term "plant lysosomes".

    Peroxisomes or Uricosomes

    • In animal cells, peroxisomes are involved in peroxide (H2O2) metabolism.
    • They contain enzymes like urate oxidase, amino acid oxidase, and peroxidase.
    • Peroxidase induces the oxidation of amino acids to produce H2O2.
    • Catalase degrades H2O2 into water and oxygen.
    • In plant cells, peroxisomes occur in cells of green tissues and are involved in photorespiration.
    • They also detoxify alcohol in liver cells.

    Cytoskeleton

    • The cytoskeleton is an elaborate network of filamentous proteinaceous structures present in the cytoplasm.
    • It provides mechanical support, motility, and maintains the shape of the cell.
    • The cytoskeleton consists of microtubules, microfilaments, and intermediate filaments.

    Microtubules

    • Microtubules are composed of protein tubulin.
    • In plant cells, microtubules are often found associated with the cell wall.
    • They probably transport cell wall material from the Golgi body to the outside of the cell.
    • During cell division, microtubules form spindle fibers.

    Microfilaments

    • Microfilaments are composed of contractile protein actin.
    • Actin is concerned with muscle contraction.

    Intermediate Filaments

    • Intermediate filaments have a size/diameter between microfilaments and microtubules.
    • They form basket-like structures around the nucleus.

    Cilia and Flagella

    • Cilia are small, hair-like structures that work like oars, causing movement of either the cell or surrounding fluid.
    • Cilia are small in size, with a large number per cell, beating in a coordinated manner to facilitate locomotion, attachment, and feeding.
    • Flagella are longer than cilia, fewer in number, and beat independently in a non-coordinated manner, responsible only for locomotion.

    Centrioles

    • Centrioles are short, cylindrical structures with a 9 + 0 pattern of microtubule triplets, found in pairs near the nucleus in animal cells, except mature mammalian RBCs.
    • Centrioles move to the poles and form asters during cell division, organizing spindle fibers.
    • The region surrounding the centriole pair is known as the centrosphere, and together they form the centrosome.

    Nucleic Acids

    • Nucleic acids are long-chain macromolecules, comprising Deoxyribonucleic Acid (DNA) and Ribonucleic Acid (RNA).
    • Nucleotides are the basic units of nucleic acids, consisting of a pentose sugar, phosphoric acid, and a nitrogen base.

    Nucleotides

    • Nucleotides contain one of two types of pentose sugars: ribose or deoxyribose.
    • Nitrogen bases are heterocyclic compounds, classified as purines (Adenine, Guanine) and pyrimidines (Cytosine, Thymine, Uracil).
    • A combination of a nitrogen base with a pentose sugar is known as a nucleoside.

    Cilia and Flagella

    • Cilia are small, hair-like structures that work like oars, causing movement of either the cell or surrounding fluid.
    • Cilia are small in size, with a large number per cell, beating in a coordinated manner to facilitate locomotion, attachment, and feeding.
    • Flagella are longer than cilia, fewer in number, and beat independently in a non-coordinated manner, responsible only for locomotion.

    Centrioles

    • Centrioles are short, cylindrical structures with a 9 + 0 pattern of microtubule triplets, found in pairs near the nucleus in animal cells, except mature mammalian RBCs.
    • Centrioles move to the poles and form asters during cell division, organizing spindle fibers.
    • The region surrounding the centriole pair is known as the centrosphere, and together they form the centrosome.

    Nucleic Acids

    • Nucleic acids are long-chain macromolecules, comprising Deoxyribonucleic Acid (DNA) and Ribonucleic Acid (RNA).
    • Nucleotides are the basic units of nucleic acids, consisting of a pentose sugar, phosphoric acid, and a nitrogen base.

    Nucleotides

    • Nucleotides contain one of two types of pentose sugars: ribose or deoxyribose.
    • Nitrogen bases are heterocyclic compounds, classified as purines (Adenine, Guanine) and pyrimidines (Cytosine, Thymine, Uracil).
    • A combination of a nitrogen base with a pentose sugar is known as a nucleoside.

    Cilia and Flagella

    • Cilia are small, hair-like structures that work like oars, causing movement of either the cell or surrounding fluid.
    • Cilia are small in size, with a large number per cell, beating in a coordinated manner to facilitate locomotion, attachment, and feeding.
    • Flagella are longer than cilia, fewer in number, and beat independently in a non-coordinated manner, responsible only for locomotion.

    Centrioles

    • Centrioles are short, cylindrical structures with a 9 + 0 pattern of microtubule triplets, found in pairs near the nucleus in animal cells, except mature mammalian RBCs.
    • Centrioles move to the poles and form asters during cell division, organizing spindle fibers.
    • The region surrounding the centriole pair is known as the centrosphere, and together they form the centrosome.

    Nucleic Acids

    • Nucleic acids are long-chain macromolecules, comprising Deoxyribonucleic Acid (DNA) and Ribonucleic Acid (RNA).
    • Nucleotides are the basic units of nucleic acids, consisting of a pentose sugar, phosphoric acid, and a nitrogen base.

    Nucleotides

    • Nucleotides contain one of two types of pentose sugars: ribose or deoxyribose.
    • Nitrogen bases are heterocyclic compounds, classified as purines (Adenine, Guanine) and pyrimidines (Cytosine, Thymine, Uracil).
    • A combination of a nitrogen base with a pentose sugar is known as a nucleoside.

    Deoxyribonucleic Acid (DNA)

    • DNA model was given by Watson and Crick
    • Consists of two polynucleotide chains that form a double helical staircase
    • Chains are joined together by weak hydrogen bonds between nitrogen bases

    Nitrogen Bases in DNA

    • Purines: Adenine (A) and Guanine (G)
    • Pyrimidines: Cytosine (C) and Thymine (T)
    • Base pairing: Adenine (A) pairs with Thymine (T) with two hydrogen bonds, and Cytosine (C) pairs with Guanine (G) with three hydrogen bonds
    • A + G = C + T, establishing Chargaff's rule of base equivalence

    Structure of DNA

    • Double helix is twisted, taking a complete turn after every 34 A
    • 10 nitrogen base pairs in a complete turn
    • Width of DNA molecule is 20 A
    • DNA found in mitochondria, plastids, and prokaryotes is generally circular, uncovered with protein (naked)

    Ribonucleic Acid (RNA)

    • Occurs in all living cells and viruses
    • Found in cytoplasm and nucleus of eukaryotic cells
    • Can be genetic material in some viruses (genetic RNA)
    • Non-genetic RNA found in nucleus, cytoplasm, ribosomes, chloroplasts, and mitochondria

    Structure of RNA

    • Single-stranded molecule, shorter than DNA
    • Uracil replaces thymine as nitrogen base
    • Pentose sugar is ribose
    • Occurs in three forms: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA)

    Significance of DNA

    • Controls all cell activities directly and indirectly
    • Unique feature: ability to duplicate itself during cell division (replication)
    • Genetic material, containing information for protein synthesis
    • Can undergo mutations and recombination, leading to variations and speciation

    Deoxyribonucleic Acid (DNA)

    • DNA model was given by Watson and Crick
    • Consists of two polynucleotide chains that form a double helical staircase
    • Chains are joined together by weak hydrogen bonds between nitrogen bases

    Nitrogen Bases in DNA

    • Purines: Adenine (A) and Guanine (G)
    • Pyrimidines: Cytosine (C) and Thymine (T)
    • Base pairing: Adenine (A) pairs with Thymine (T) with two hydrogen bonds, and Cytosine (C) pairs with Guanine (G) with three hydrogen bonds
    • A + G = C + T, establishing Chargaff's rule of base equivalence

    Structure of DNA

    • Double helix is twisted, taking a complete turn after every 34 A
    • 10 nitrogen base pairs in a complete turn
    • Width of DNA molecule is 20 A
    • DNA found in mitochondria, plastids, and prokaryotes is generally circular, uncovered with protein (naked)

    Ribonucleic Acid (RNA)

    • Occurs in all living cells and viruses
    • Found in cytoplasm and nucleus of eukaryotic cells
    • Can be genetic material in some viruses (genetic RNA)
    • Non-genetic RNA found in nucleus, cytoplasm, ribosomes, chloroplasts, and mitochondria

    Structure of RNA

    • Single-stranded molecule, shorter than DNA
    • Uracil replaces thymine as nitrogen base
    • Pentose sugar is ribose
    • Occurs in three forms: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA)

    Significance of DNA

    • Controls all cell activities directly and indirectly
    • Unique feature: ability to duplicate itself during cell division (replication)
    • Genetic material, containing information for protein synthesis
    • Can undergo mutations and recombination, leading to variations and speciation

    Nucleus

    • Discovered by Robert Brown in 1831
    • Most cells have a single nucleus, but some protists like paramecium have two nuclei (binucleated), and some cells of bone marrow, striated muscles, certain algae, and fungi have multiple nuclei (multinucleated)

    Nuclear Envelope

    • Double-membranous structure surrounding the nucleus, separating it from the cytoplasm
    • Has pores called nucleopores that allow large macromolecules and ribosomes to pass through

    Nucleoplasm

    • Contains nucleoproteins, nucleotides, and enzymes required for DNA synthesis
    • DNA is a genetic material that contains all the genetic information required for an organism's growth, development, reproduction, metabolism, and behavior

    Chromatin

    • Hereditary DNA-protein complex that appears as a network called chromatin reticulum
    • Chromatin fibers condense to form a definite number of thread-like structures called chromosomes

    Nucleolus

    • Naked, rounded or irregular body attached to chromatin at a specific region
    • Discovered by Fontana in 1781 and named by Bowman in 1840
    • Principal site for the development of ribosomal RNA and the formation of ribosomes

    Functions of Nucleus

    • Contains all genetic information required for an organism's growth, development, reproduction, metabolism, and behavior
    • Passes genetic information to daughter cells
    • Takes part in the formation of ribosomes
    • Develops genetic variations that contribute to evolution
    • Controls all metabolic activities of the cell

    Prokaryotes and Eukaryotes

    • Prokaryotes: organisms that lack a nuclear membrane and have genetic material in the form of a nucleoid (e.g., bacteria, blue-green algae, Mycoplasma)
    • Eukaryotes: organisms with cells that have a well-organized nucleus with a nuclear membrane (e.g., all plant and animal cells, fungi)

    Chromosomes

    • Rod-shaped or thread-like DNA-containing structures located in the nucleus of eukaryotes
    • Usually ring-shaped in prokaryotes and contain all or most of an organism's genes
    • In eukaryotes, DNA occurs in both the nucleus and semi-autonomous organelles like mitochondria and plastids

    Structure of Chromosomes

    • A replicated chromosome consists of two identical halves (chromatids) held together at the centromere
    • Each sister chromatid has a kinetochore, a specialized protein structure located at the centromere
    • Chromatin fibers are composed of DNA combined with proteins and are very long and greatly coiled to be accommodated in a short chromatid

    Chromosome Classification

    • Chromosomes can have either equal or unequal arms depending on the position of the centromere
    • Four types of chromosomes: metacentric, submetacentric, acrocentric, and telocentric, based on the position of the centromere

    Nucleus

    • Discovered by Robert Brown in 1831
    • Most cells have a single nucleus, but some protists like paramecium have two nuclei (binucleated), and some cells of bone marrow, striated muscles, certain algae, and fungi have multiple nuclei (multinucleated)

    Nuclear Envelope

    • Double-membranous structure surrounding the nucleus, separating it from the cytoplasm
    • Has pores called nucleopores that allow large macromolecules and ribosomes to pass through

    Nucleoplasm

    • Contains nucleoproteins, nucleotides, and enzymes required for DNA synthesis
    • DNA is a genetic material that contains all the genetic information required for an organism's growth, development, reproduction, metabolism, and behavior

    Chromatin

    • Hereditary DNA-protein complex that appears as a network called chromatin reticulum
    • Chromatin fibers condense to form a definite number of thread-like structures called chromosomes

    Nucleolus

    • Naked, rounded or irregular body attached to chromatin at a specific region
    • Discovered by Fontana in 1781 and named by Bowman in 1840
    • Principal site for the development of ribosomal RNA and the formation of ribosomes

    Functions of Nucleus

    • Contains all genetic information required for an organism's growth, development, reproduction, metabolism, and behavior
    • Passes genetic information to daughter cells
    • Takes part in the formation of ribosomes
    • Develops genetic variations that contribute to evolution
    • Controls all metabolic activities of the cell

    Prokaryotes and Eukaryotes

    • Prokaryotes: organisms that lack a nuclear membrane and have genetic material in the form of a nucleoid (e.g., bacteria, blue-green algae, Mycoplasma)
    • Eukaryotes: organisms with cells that have a well-organized nucleus with a nuclear membrane (e.g., all plant and animal cells, fungi)

    Chromosomes

    • Rod-shaped or thread-like DNA-containing structures located in the nucleus of eukaryotes
    • Usually ring-shaped in prokaryotes and contain all or most of an organism's genes
    • In eukaryotes, DNA occurs in both the nucleus and semi-autonomous organelles like mitochondria and plastids

    Structure of Chromosomes

    • A replicated chromosome consists of two identical halves (chromatids) held together at the centromere
    • Each sister chromatid has a kinetochore, a specialized protein structure located at the centromere
    • Chromatin fibers are composed of DNA combined with proteins and are very long and greatly coiled to be accommodated in a short chromatid

    Chromosome Classification

    • Chromosomes can have either equal or unequal arms depending on the position of the centromere
    • Four types of chromosomes: metacentric, submetacentric, acrocentric, and telocentric, based on the position of the centromere

    Nucleus

    • Discovered by Robert Brown in 1831
    • Most cells have a single nucleus, but some protists like paramecium have two nuclei (binucleated), and some cells of bone marrow, striated muscles, certain algae, and fungi have multiple nuclei (multinucleated)

    Nuclear Envelope

    • Double-membranous structure surrounding the nucleus, separating it from the cytoplasm
    • Has pores called nucleopores that allow large macromolecules and ribosomes to pass through

    Nucleoplasm

    • Contains nucleoproteins, nucleotides, and enzymes required for DNA synthesis
    • DNA is a genetic material that contains all the genetic information required for an organism's growth, development, reproduction, metabolism, and behavior

    Chromatin

    • Hereditary DNA-protein complex that appears as a network called chromatin reticulum
    • Chromatin fibers condense to form a definite number of thread-like structures called chromosomes

    Nucleolus

    • Naked, rounded or irregular body attached to chromatin at a specific region
    • Discovered by Fontana in 1781 and named by Bowman in 1840
    • Principal site for the development of ribosomal RNA and the formation of ribosomes

    Functions of Nucleus

    • Contains all genetic information required for an organism's growth, development, reproduction, metabolism, and behavior
    • Passes genetic information to daughter cells
    • Takes part in the formation of ribosomes
    • Develops genetic variations that contribute to evolution
    • Controls all metabolic activities of the cell

    Prokaryotes and Eukaryotes

    • Prokaryotes: organisms that lack a nuclear membrane and have genetic material in the form of a nucleoid (e.g., bacteria, blue-green algae, Mycoplasma)
    • Eukaryotes: organisms with cells that have a well-organized nucleus with a nuclear membrane (e.g., all plant and animal cells, fungi)

    Chromosomes

    • Rod-shaped or thread-like DNA-containing structures located in the nucleus of eukaryotes
    • Usually ring-shaped in prokaryotes and contain all or most of an organism's genes
    • In eukaryotes, DNA occurs in both the nucleus and semi-autonomous organelles like mitochondria and plastids

    Structure of Chromosomes

    • A replicated chromosome consists of two identical halves (chromatids) held together at the centromere
    • Each sister chromatid has a kinetochore, a specialized protein structure located at the centromere
    • Chromatin fibers are composed of DNA combined with proteins and are very long and greatly coiled to be accommodated in a short chromatid

    Chromosome Classification

    • Chromosomes can have either equal or unequal arms depending on the position of the centromere
    • Four types of chromosomes: metacentric, submetacentric, acrocentric, and telocentric, based on the position of the centromere

    Homologous Chromosomes

    • Homologous chromosomes are two chromosomes of the same type, size, morphology, and arrangement of gene loci position.
    • They occur in somatic cells of animals and vascular plants, possessing a diploid number of chromosomes.
    • One homologous chromosome is derived from the father, and the other from the mother.

    Genomes

    • A genome is a complete set of chromosomes (all genes) as found in gametes, where each chromosome is represented singly.
    • Somatic cells of animals and higher plants generally possess two sets of chromosomes, a condition called diploid (2n).
    • Gametes possess half the number of chromosomes, a condition called haploid.

    Chromosome Number

    • The number of chromosomes is definite for each species.
    • In humans, each body cell has 46 chromosomes.

    Sex Chromosomes and Autosomes

    • Sex chromosomes determine the sex of an individual in dioecious or unisexual organisms.
    • Sex chromosomes are also called allosomes.
    • Chromosomes other than sex chromosomes are called autosomes.

    Genes

    • Each chromosome consists of a number of genes, which are short segments of DNA.
    • Genes are arranged in a linear order on a chromosome.
    • Each gene has a specific position and carries a specific function.
    • A set of genes is sometimes required for a single function.

    Cell Cycle and Cell Division

    • Living and dividing cells pass through a regular sequence of growth and division called the cell cycle.
    • The timing and rate of cell division are crucial to normal growth and development.
    • Cell division functions in growth, repair, and reproduction.
    • There are two types of cell division: mitosis and meiosis.
    • Mitosis produces two genetically identical daughter cells and conserves the chromosome number (2n).
    • Meiosis occurs in sexually reproducing organisms and results in cells with half the chromosome number (n) of the parent cell.

    Homologous Chromosomes

    • Homologous chromosomes are two chromosomes of the same type, size, morphology, and arrangement of gene loci position.
    • They occur in somatic cells of animals and vascular plants, possessing a diploid number of chromosomes.
    • One homologous chromosome is derived from the father, and the other from the mother.

    Genomes

    • A genome is a complete set of chromosomes (all genes) as found in gametes, where each chromosome is represented singly.
    • Somatic cells of animals and higher plants generally possess two sets of chromosomes, a condition called diploid (2n).
    • Gametes possess half the number of chromosomes, a condition called haploid.

    Chromosome Number

    • The number of chromosomes is definite for each species.
    • In humans, each body cell has 46 chromosomes.

    Sex Chromosomes and Autosomes

    • Sex chromosomes determine the sex of an individual in dioecious or unisexual organisms.
    • Sex chromosomes are also called allosomes.
    • Chromosomes other than sex chromosomes are called autosomes.

    Genes

    • Each chromosome consists of a number of genes, which are short segments of DNA.
    • Genes are arranged in a linear order on a chromosome.
    • Each gene has a specific position and carries a specific function.
    • A set of genes is sometimes required for a single function.

    Cell Cycle and Cell Division

    • Living and dividing cells pass through a regular sequence of growth and division called the cell cycle.
    • The timing and rate of cell division are crucial to normal growth and development.
    • Cell division functions in growth, repair, and reproduction.
    • There are two types of cell division: mitosis and meiosis.
    • Mitosis produces two genetically identical daughter cells and conserves the chromosome number (2n).
    • Meiosis occurs in sexually reproducing organisms and results in cells with half the chromosome number (n) of the parent cell.

    Homologous Chromosomes

    • Homologous chromosomes are two chromosomes of the same type, size, morphology, and arrangement of gene loci position.
    • They occur in somatic cells of animals and vascular plants, possessing a diploid number of chromosomes.
    • One homologous chromosome is derived from the father, and the other from the mother.

    Genomes

    • A genome is a complete set of chromosomes (all genes) as found in gametes, where each chromosome is represented singly.
    • Somatic cells of animals and higher plants generally possess two sets of chromosomes, a condition called diploid (2n).
    • Gametes possess half the number of chromosomes, a condition called haploid.

    Chromosome Number

    • The number of chromosomes is definite for each species.
    • In humans, each body cell has 46 chromosomes.

    Sex Chromosomes and Autosomes

    • Sex chromosomes determine the sex of an individual in dioecious or unisexual organisms.
    • Sex chromosomes are also called allosomes.
    • Chromosomes other than sex chromosomes are called autosomes.

    Genes

    • Each chromosome consists of a number of genes, which are short segments of DNA.
    • Genes are arranged in a linear order on a chromosome.
    • Each gene has a specific position and carries a specific function.
    • A set of genes is sometimes required for a single function.

    Cell Cycle and Cell Division

    • Living and dividing cells pass through a regular sequence of growth and division called the cell cycle.
    • The timing and rate of cell division are crucial to normal growth and development.
    • Cell division functions in growth, repair, and reproduction.
    • There are two types of cell division: mitosis and meiosis.
    • Mitosis produces two genetically identical daughter cells and conserves the chromosome number (2n).
    • Meiosis occurs in sexually reproducing organisms and results in cells with half the chromosome number (n) of the parent cell.

    Cell Growth and Division

    • Cells obtain organic and inorganic materials from their environment, metabolize them, and dispose of waste products to generate bioenergy and synthesize macromolecular components, leading to cell growth.
    • The metabolic reactions are controlled by the genetic material in the nucleus.

    Factors Limiting Cell Size and Promoting Cell Division

    • Two factors limit cell size and promote cell division: the ratio of cell volume to surface area and the capacity of the nucleus.
    • As a cell grows, the volume increases faster than the surface area, making it difficult for the cell membrane to exchange nutrients and waste products.
    • The nucleus must be able to provide enough information to meet the cell's needs, and larger cells need multiple nuclei to achieve this.

    Phases of the Cell Cycle

    • The cell cycle consists of five major phases: G1, S, G2 (interphase), mitosis, and cytokinesis.
    • Interphase consists of G1, S, and G2 phases, during which the cell grows, replicates DNA, and prepares for cell division.
    • Mitosis is the actual dividing of the nucleus, divided into four phases: prophase, metaphase, anaphase, and telophase.
    • Cytokinesis is the separate process of dividing the cell into two daughter cells.

    Mitosis

    • Prophase: nuclear membrane disintegrates, chromosomes condense, nucleolus disappears, and mitotic spindle forms.
    • Metaphase: chromosomes line up on the metaphase plate, centrosomes are at opposite poles, and spindle fibers connect to kinetochores.
    • Anaphase: centromeres separate, and spindle fibers pull apart sister chromosomes.
    • Telophase: chromosomes cluster at opposite ends, nuclear membrane reforms, and chromosomes unravel to their normal condition.

    Cytokinesis

    • Cytokinesis is the process of dividing the cell into two daughter cells, accomplishing the segregation of duplicated chromosomes into two nuclei.

    Cell Growth and Division

    • Cells obtain organic and inorganic materials from their environment, metabolize them, and dispose of waste products to generate bioenergy and synthesize macromolecular components, leading to cell growth.
    • The metabolic reactions are controlled by the genetic material in the nucleus.

    Factors Limiting Cell Size and Promoting Cell Division

    • Two factors limit cell size and promote cell division: the ratio of cell volume to surface area and the capacity of the nucleus.
    • As a cell grows, the volume increases faster than the surface area, making it difficult for the cell membrane to exchange nutrients and waste products.
    • The nucleus must be able to provide enough information to meet the cell's needs, and larger cells need multiple nuclei to achieve this.

    Phases of the Cell Cycle

    • The cell cycle consists of five major phases: G1, S, G2 (interphase), mitosis, and cytokinesis.
    • Interphase consists of G1, S, and G2 phases, during which the cell grows, replicates DNA, and prepares for cell division.
    • Mitosis is the actual dividing of the nucleus, divided into four phases: prophase, metaphase, anaphase, and telophase.
    • Cytokinesis is the separate process of dividing the cell into two daughter cells.

    Mitosis

    • Prophase: nuclear membrane disintegrates, chromosomes condense, nucleolus disappears, and mitotic spindle forms.
    • Metaphase: chromosomes line up on the metaphase plate, centrosomes are at opposite poles, and spindle fibers connect to kinetochores.
    • Anaphase: centromeres separate, and spindle fibers pull apart sister chromosomes.
    • Telophase: chromosomes cluster at opposite ends, nuclear membrane reforms, and chromosomes unravel to their normal condition.

    Cytokinesis

    • Cytokinesis is the process of dividing the cell into two daughter cells, accomplishing the segregation of duplicated chromosomes into two nuclei.

    Cytokinesis

    • Cytokinesis is the process of dividing a cell into two daughter cells after mitosis.
    • In animal cells, cytokinesis occurs by constriction and furrow formation.
    • Microtubules and microfilaments arrange on the equator to form midbody and a contractile ring.
    • The contractile ring, composed of actin and myosin, contracts to form a furrow that deepens continuously until the cell divides.
    • In animal cells, cytokinesis occurs in centripetal order.

    Cytokinesis in Plant Cells

    • Cytokinesis in plant cells takes place by cell plate formation due to the presence of a rigid cell wall.
    • Golgi vesicle aggregation in the spindle midzone is organized by phragmoplast.
    • Membrane of Golgi vesicles fuse to form a plate-like structure called cell plate.
    • Cell plate is modified into middle lamella.
    • In plant cells, cytokinesis occurs in centrifugal order.

    Importance of Mitosis

    • Mitosis is essential for replacing worn-out and damaged tissue.
    • It helps in producing identical copies of cells, which aids in repairing damaged cells.

    Meiosis

    • Meiosis is a form of cell division that produces gametes (sex cells, or sperm and ova) with the haploid chromosome number (23).
    • Meiosis consists of two stages: meiosis I (reduction division) and meiosis II (equational division).
    • Meiosis I is when homologous chromosomes separate, while meiosis II is similar to mitosis.

    Meiosis I

    • Synapsis (pairing of homologous chromosomes) and crossing-over (exchange of genetic material) occur during prophase I.
    • Chiasmata (cross-like structures) form, visible manifestations of the cross-over event.
    • Homologous pairs of chromosomes are lined up in double file along the metaphasic plate during metaphase I.
    • Homologous chromosomes are separated during anaphase I and migrate to opposite poles.
    • Homologous pairs continue to separate until they reach the poles of the cell during telophase I.

    Meiosis II

    • Meiosis II is functionally the same as mitosis and consists of the same phases: prophase II, metaphase II, anaphase II, telophase II, and cytokinesis.
    • The chromosome number remains haploid, and daughter cells are genetically identical to the parent cell.

    Meiosis and Genetic Variation

    • Three types of genetic variation result from the processes of meiosis and fertilization: independent assortment of chromosomes, crossing-over, and random fertilization of an ovum by a sperm.

    Cytokinesis

    • Cytokinesis is the process of dividing a cell into two daughter cells after mitosis.
    • In animal cells, cytokinesis occurs by constriction and furrow formation.
    • Microtubules and microfilaments arrange on the equator to form midbody and a contractile ring.
    • The contractile ring, composed of actin and myosin, contracts to form a furrow that deepens continuously until the cell divides.
    • In animal cells, cytokinesis occurs in centripetal order.

    Cytokinesis in Plant Cells

    • Cytokinesis in plant cells takes place by cell plate formation due to the presence of a rigid cell wall.
    • Golgi vesicle aggregation in the spindle midzone is organized by phragmoplast.
    • Membrane of Golgi vesicles fuse to form a plate-like structure called cell plate.
    • Cell plate is modified into middle lamella.
    • In plant cells, cytokinesis occurs in centrifugal order.

    Importance of Mitosis

    • Mitosis is essential for replacing worn-out and damaged tissue.
    • It helps in producing identical copies of cells, which aids in repairing damaged cells.

    Meiosis

    • Meiosis is a form of cell division that produces gametes (sex cells, or sperm and ova) with the haploid chromosome number (23).
    • Meiosis consists of two stages: meiosis I (reduction division) and meiosis II (equational division).
    • Meiosis I is when homologous chromosomes separate, while meiosis II is similar to mitosis.

    Meiosis I

    • Synapsis (pairing of homologous chromosomes) and crossing-over (exchange of genetic material) occur during prophase I.
    • Chiasmata (cross-like structures) form, visible manifestations of the cross-over event.
    • Homologous pairs of chromosomes are lined up in double file along the metaphasic plate during metaphase I.
    • Homologous chromosomes are separated during anaphase I and migrate to opposite poles.
    • Homologous pairs continue to separate until they reach the poles of the cell during telophase I.

    Meiosis II

    • Meiosis II is functionally the same as mitosis and consists of the same phases: prophase II, metaphase II, anaphase II, telophase II, and cytokinesis.
    • The chromosome number remains haploid, and daughter cells are genetically identical to the parent cell.

    Meiosis and Genetic Variation

    • Three types of genetic variation result from the processes of meiosis and fertilization: independent assortment of chromosomes, crossing-over, and random fertilization of an ovum by a sperm.

    Cytokinesis

    • Cytokinesis is the process of dividing a cell into two daughter cells after mitosis.
    • In animal cells, cytokinesis occurs by constriction and furrow formation.
    • Microtubules and microfilaments arrange on the equator to form midbody and a contractile ring.
    • The contractile ring, composed of actin and myosin, contracts to form a furrow that deepens continuously until the cell divides.
    • In animal cells, cytokinesis occurs in centripetal order.

    Cytokinesis in Plant Cells

    • Cytokinesis in plant cells takes place by cell plate formation due to the presence of a rigid cell wall.
    • Golgi vesicle aggregation in the spindle midzone is organized by phragmoplast.
    • Membrane of Golgi vesicles fuse to form a plate-like structure called cell plate.
    • Cell plate is modified into middle lamella.
    • In plant cells, cytokinesis occurs in centrifugal order.

    Importance of Mitosis

    • Mitosis is essential for replacing worn-out and damaged tissue.
    • It helps in producing identical copies of cells, which aids in repairing damaged cells.

    Meiosis

    • Meiosis is a form of cell division that produces gametes (sex cells, or sperm and ova) with the haploid chromosome number (23).
    • Meiosis consists of two stages: meiosis I (reduction division) and meiosis II (equational division).
    • Meiosis I is when homologous chromosomes separate, while meiosis II is similar to mitosis.

    Meiosis I

    • Synapsis (pairing of homologous chromosomes) and crossing-over (exchange of genetic material) occur during prophase I.
    • Chiasmata (cross-like structures) form, visible manifestations of the cross-over event.
    • Homologous pairs of chromosomes are lined up in double file along the metaphasic plate during metaphase I.
    • Homologous chromosomes are separated during anaphase I and migrate to opposite poles.
    • Homologous pairs continue to separate until they reach the poles of the cell during telophase I.

    Meiosis II

    • Meiosis II is functionally the same as mitosis and consists of the same phases: prophase II, metaphase II, anaphase II, telophase II, and cytokinesis.
    • The chromosome number remains haploid, and daughter cells are genetically identical to the parent cell.

    Meiosis and Genetic Variation

    • Three types of genetic variation result from the processes of meiosis and fertilization: independent assortment of chromosomes, crossing-over, and random fertilization of an ovum by a sperm.

    Meiosis and Independent Assortment

    • Independent assortment of chromosomes occurs during meiosis as homologous pairs of chromosomes separate randomly on the metaphase plate.
    • This process results in a 50% chance of a gamete receiving a maternal or paternal chromosome.
    • Crossover and random alignment of chromosomes during metaphase II increase the possible types of gametes.

    Plant Cell Characteristics

    • Plant cells are typically larger in size.
    • Plant cells have a rigid cell wall and cannot change shape.
    • They contain plastids, and those exposed to sunlight have chloroplasts.
    • Mature plant cells have a large central vacuole.
    • The nucleus is located on one side in the peripheral cytoplasm.
    • Centrioles are usually absent except in motile cells of lower plants.
    • Golgi apparatus consists of distinct, unconnected units called dictyosomes.
    • Lysosomes are rare, and their function is performed by specialized vacuoles.
    • Glyoxysomes may be present, and reserve food is stored as starch or fat.
    • Plant cells do not burst in hypotonic solutions due to their cell wall.

    Animal Cell Characteristics

    • Animal cells are relatively smaller in size.
    • They have a thin, flexible plasma membrane and can change shape.
    • Plastids are usually absent.
    • Animal cells have many small vacuoles, and the nucleus is typically located in the center.
    • Centrioles are practically present in all animal cells.
    • Golgi apparatus is either localized or consists of a well-connected single complex.
    • Lysosomes are always present, and glyoxysomes are absent.
    • Reserve food is stored as glycogen and fat.
    • Animal cells typically burst in hypotonic solutions due to the absence of a cell wall.

    Prokaryotic and Eukaryotic Cell Characteristics

    Prokaryotes

    • Prokaryotic cells are typically 0.2-2.0 μm in diameter.
    • They have no nuclear membrane or nucleoli.
    • Membrane-enclosed cell organelles are absent.
    • A cell wall is usually present, made up of peptidoglycan.
    • They have 70S type ribosomes and single circular DNA.

    Eukaryotes

    • Eukaryotic cells are typically 10-100 μm in diameter.
    • They have a true nucleus with a nuclear membrane and nucleoli.
    • Membrane-enclosed cell organelles are present, such as lysosomes, Golgi complex, endoplasmic reticulum, mitochondria, and chloroplasts.
    • A cell wall is present when made up of cellulose or chitin.
    • They have 80S type ribosomes and linear DNA organized into multiple chromosomes.

    Meiosis and Independent Assortment

    • Independent assortment of chromosomes occurs during meiosis as homologous pairs of chromosomes separate randomly on the metaphase plate.
    • This process results in a 50% chance of a gamete receiving a maternal or paternal chromosome.
    • Crossover and random alignment of chromosomes during metaphase II increase the possible types of gametes.

    Plant Cell Characteristics

    • Plant cells are typically larger in size.
    • Plant cells have a rigid cell wall and cannot change shape.
    • They contain plastids, and those exposed to sunlight have chloroplasts.
    • Mature plant cells have a large central vacuole.
    • The nucleus is located on one side in the peripheral cytoplasm.
    • Centrioles are usually absent except in motile cells of lower plants.
    • Golgi apparatus consists of distinct, unconnected units called dictyosomes.
    • Lysosomes are rare, and their function is performed by specialized vacuoles.
    • Glyoxysomes may be present, and reserve food is stored as starch or fat.
    • Plant cells do not burst in hypotonic solutions due to their cell wall.

    Animal Cell Characteristics

    • Animal cells are relatively smaller in size.
    • They have a thin, flexible plasma membrane and can change shape.
    • Plastids are usually absent.
    • Animal cells have many small vacuoles, and the nucleus is typically located in the center.
    • Centrioles are practically present in all animal cells.
    • Golgi apparatus is either localized or consists of a well-connected single complex.
    • Lysosomes are always present, and glyoxysomes are absent.
    • Reserve food is stored as glycogen and fat.
    • Animal cells typically burst in hypotonic solutions due to the absence of a cell wall.

    Prokaryotic and Eukaryotic Cell Characteristics

    Prokaryotes

    • Prokaryotic cells are typically 0.2-2.0 μm in diameter.
    • They have no nuclear membrane or nucleoli.
    • Membrane-enclosed cell organelles are absent.
    • A cell wall is usually present, made up of peptidoglycan.
    • They have 70S type ribosomes and single circular DNA.

    Eukaryotes

    • Eukaryotic cells are typically 10-100 μm in diameter.
    • They have a true nucleus with a nuclear membrane and nucleoli.
    • Membrane-enclosed cell organelles are present, such as lysosomes, Golgi complex, endoplasmic reticulum, mitochondria, and chloroplasts.
    • A cell wall is present when made up of cellulose or chitin.
    • They have 80S type ribosomes and linear DNA organized into multiple chromosomes.

    Meiosis and Independent Assortment

    • Independent assortment of chromosomes occurs during meiosis as homologous pairs of chromosomes separate randomly on the metaphase plate.
    • This process results in a 50% chance of a gamete receiving a maternal or paternal chromosome.
    • Crossover and random alignment of chromosomes during metaphase II increase the possible types of gametes.

    Plant Cell Characteristics

    • Plant cells are typically larger in size.
    • Plant cells have a rigid cell wall and cannot change shape.
    • They contain plastids, and those exposed to sunlight have chloroplasts.
    • Mature plant cells have a large central vacuole.
    • The nucleus is located on one side in the peripheral cytoplasm.
    • Centrioles are usually absent except in motile cells of lower plants.
    • Golgi apparatus consists of distinct, unconnected units called dictyosomes.
    • Lysosomes are rare, and their function is performed by specialized vacuoles.
    • Glyoxysomes may be present, and reserve food is stored as starch or fat.
    • Plant cells do not burst in hypotonic solutions due to their cell wall.

    Animal Cell Characteristics

    • Animal cells are relatively smaller in size.
    • They have a thin, flexible plasma membrane and can change shape.
    • Plastids are usually absent.
    • Animal cells have many small vacuoles, and the nucleus is typically located in the center.
    • Centrioles are practically present in all animal cells.
    • Golgi apparatus is either localized or consists of a well-connected single complex.
    • Lysosomes are always present, and glyoxysomes are absent.
    • Reserve food is stored as glycogen and fat.
    • Animal cells typically burst in hypotonic solutions due to the absence of a cell wall.

    Prokaryotic and Eukaryotic Cell Characteristics

    Prokaryotes

    • Prokaryotic cells are typically 0.2-2.0 μm in diameter.
    • They have no nuclear membrane or nucleoli.
    • Membrane-enclosed cell organelles are absent.
    • A cell wall is usually present, made up of peptidoglycan.
    • They have 70S type ribosomes and single circular DNA.

    Eukaryotes

    • Eukaryotic cells are typically 10-100 μm in diameter.
    • They have a true nucleus with a nuclear membrane and nucleoli.
    • Membrane-enclosed cell organelles are present, such as lysosomes, Golgi complex, endoplasmic reticulum, mitochondria, and chloroplasts.
    • A cell wall is present when made up of cellulose or chitin.
    • They have 80S type ribosomes and linear DNA organized into multiple chromosomes.

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    Learn about the fundamental unit of life, the cell, and its structure and function in living organisms. Explore the history of cytology and the invention of the microscope.

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