Podcast
Questions and Answers
What is the smallest unit that can carry out all activities associated with life?
What is the smallest unit that can carry out all activities associated with life?
The cell
What are the building blocks of complex multicellular organisms?
What are the building blocks of complex multicellular organisms?
Cells
All cells come from pre-existing cells.
All cells come from pre-existing cells.
True
What acts as a selective barrier between cell contents and the environment to support homeostasis?
What acts as a selective barrier between cell contents and the environment to support homeostasis?
Signup and view all the answers
What are specialized organelles that carry out metabolic activities?
What are specialized organelles that carry out metabolic activities?
Signup and view all the answers
Where are genetic instructions coded in cells?
Where are genetic instructions coded in cells?
Signup and view all the answers
Most cell components are measured in nanometers.
Most cell components are measured in nanometers.
Signup and view all the answers
What must pass through the plasma membrane?
What must pass through the plasma membrane?
Signup and view all the answers
What is critical for cell function?
What is critical for cell function?
Signup and view all the answers
What is an example of a strategy for increasing the ratio of surface area to volume in cells?
What is an example of a strategy for increasing the ratio of surface area to volume in cells?
Signup and view all the answers
Amoebas and white blood cells are known for maintaining a fixed shape.
Amoebas and white blood cells are known for maintaining a fixed shape.
Signup and view all the answers
What do sperm cells have that helps them move?
What do sperm cells have that helps them move?
Signup and view all the answers
What type of cells have long, thin extensions that enable them to transmit messages over great distances?
What type of cells have long, thin extensions that enable them to transmit messages over great distances?
Signup and view all the answers
What type of cells stack like building blocks to form sheet-like tissues?
What type of cells stack like building blocks to form sheet-like tissues?
Signup and view all the answers
Who was the first person to describe cells in 1665?
Who was the first person to describe cells in 1665?
Signup and view all the answers
Who discovered bacteria, protists, blood cells, and sperm cells using small lenses?
Who discovered bacteria, protists, blood cells, and sperm cells using small lenses?
Signup and view all the answers
Microscopes were sufficiently developed for biologists to seriously study cells in the early 19th century.
Microscopes were sufficiently developed for biologists to seriously study cells in the early 19th century.
Signup and view all the answers
What type of microscope uses visible light to study stained or living cells?
What type of microscope uses visible light to study stained or living cells?
Signup and view all the answers
What is the ratio of the size of the image seen with the microscope to the actual size of the object?
What is the ratio of the size of the image seen with the microscope to the actual size of the object?
Signup and view all the answers
What is the minimum distance between two points at which they can both be seen separately?
What is the minimum distance between two points at which they can both be seen separately?
Signup and view all the answers
What type of microscope is used to study the ultrastructure of cells, providing high-resolution images?
What type of microscope is used to study the ultrastructure of cells, providing high-resolution images?
Signup and view all the answers
Some electron microscopes have resolving powers less than 1 nanometer.
Some electron microscopes have resolving powers less than 1 nanometer.
Signup and view all the answers
What type of technique is used for separating parts of cells for studying?
What type of technique is used for separating parts of cells for studying?
Signup and view all the answers
What is used to spin cells broken apart, separating the extract into a pellet and a supernatant?
What is used to spin cells broken apart, separating the extract into a pellet and a supernatant?
Signup and view all the answers
What is the process called when the supernatant is centrifuged again into another pellet?
What is the process called when the supernatant is centrifuged again into another pellet?
Signup and view all the answers
What two domains of life are prokaryotic?
What two domains of life are prokaryotic?
Signup and view all the answers
Where is DNA located in prokaryotic cells?
Where is DNA located in prokaryotic cells?
Signup and view all the answers
Prokaryotes have membrane-enclosed internal organelles.
Prokaryotes have membrane-enclosed internal organelles.
Signup and view all the answers
Most prokaryotes have cell walls outside the plasma membrane.
Most prokaryotes have cell walls outside the plasma membrane.
Signup and view all the answers
Many prokaryotes have prokaryotic flagella for movement.
Many prokaryotes have prokaryotic flagella for movement.
Signup and view all the answers
What does the interior of a prokaryotic cell contain?
What does the interior of a prokaryotic cell contain?
Signup and view all the answers
What type of cells are characterized by highly organized and specialized membrane-enclosed organelles?
What type of cells are characterized by highly organized and specialized membrane-enclosed organelles?
Signup and view all the answers
What organelle contains DNA in eukaryotic cells?
What organelle contains DNA in eukaryotic cells?
Signup and view all the answers
What is the part of the cell outside the nucleus?
What is the part of the cell outside the nucleus?
Signup and view all the answers
What allows eukaryotic cells to be larger than prokaryotes?
What allows eukaryotic cells to be larger than prokaryotes?
Signup and view all the answers
All eukaryotic cells have the same set of organelles.
All eukaryotic cells have the same set of organelles.
Signup and view all the answers
What do membrane-enclosed compartments allow for in eukaryotic cells?
What do membrane-enclosed compartments allow for in eukaryotic cells?
Signup and view all the answers
Enzymes that are bound to membranes carry out chemical reactions in cells.
Enzymes that are bound to membranes carry out chemical reactions in cells.
Signup and view all the answers
Membranes allow cells to store energy.
Membranes allow cells to store energy.
Signup and view all the answers
What is the control center of the cell?
What is the control center of the cell?
Signup and view all the answers
What is the double membrane that separates nuclear contents from the cytoplasm called?
What is the double membrane that separates nuclear contents from the cytoplasm called?
Signup and view all the answers
What regulate the passage of materials between nucleoplasm and cytoplasm?
What regulate the passage of materials between nucleoplasm and cytoplasm?
Signup and view all the answers
What helps organize nuclear contents, DNA duplication, and regulating the cell cycle?
What helps organize nuclear contents, DNA duplication, and regulating the cell cycle?
Signup and view all the answers
DNA replication occurs during cell division.
DNA replication occurs during cell division.
Signup and view all the answers
DNA molecules include genes that contain coded instructions only for protein production.
DNA molecules include genes that contain coded instructions only for protein production.
Signup and view all the answers
What does the nucleus transcribe information from DNA to?
What does the nucleus transcribe information from DNA to?
Signup and view all the answers
Where does mRNA move to, where proteins are manufactured?
Where does mRNA move to, where proteins are manufactured?
Signup and view all the answers
What is DNA that associates with RNA and certain proteins called?
What is DNA that associates with RNA and certain proteins called?
Signup and view all the answers
Chromatin helps DNA molecules pack inside the nucleus as chromosomes.
Chromatin helps DNA molecules pack inside the nucleus as chromosomes.
Signup and view all the answers
How many chromosomes does the nucleus of each human cell have?
How many chromosomes does the nucleus of each human cell have?
Signup and view all the answers
What is the organelle that synthesizes ribosomal RNA (rRNA)?
What is the organelle that synthesizes ribosomal RNA (rRNA)?
Signup and view all the answers
Proteins needed to make ribosomes are synthesized in the cytoplasm and imported into the nucleolus.
Proteins needed to make ribosomes are synthesized in the cytoplasm and imported into the nucleolus.
Signup and view all the answers
What are assembled into ribosomal subunits that leave the nucleus through nuclear pores?
What are assembled into ribosomal subunits that leave the nucleus through nuclear pores?
Signup and view all the answers
Study Notes
Cell Organization
- Cells are the basic unit of life capable of carrying out all life activities.
- Most prokaryotes and protists consist of a single cell, while most plants and animals are multicellular.
- Cells are diverse and versatile building blocks of complex multicellular organisms.
Cell Theory
- Cells are the basic living units of organization and function in all organisms.
- All cells come from other cells.
- All living cells share a common origin due to similarities in their structures and molecules.
Cell Homeostasis & Function
- Cells maintain homeostasis by using a selectively permeable plasma membrane.
- This membrane separates the cell's contents from the external environment.
- Cells contain specialized organelles for metabolic processes.
- Each cell has genetic instructions in DNA.
Cell Size
- Cell components are measured in nanometers (nm).
- Everything entering or exiting the cell passes through the plasma membrane.
- Ratio of surface area to volume is crucial for cell function.
- Cell shape variations are strategies for increasing the surface area to volume ratio. (example: microvilli)
Cell Size and Shape
- Cell shape is adapted to function. Examples include:
- Amoebas and white blood cells changing shape for movement.
- Sperm cells with whiplike tails for locomotion.
- Nerve cells with extensions for transmitting messages over long distances.
- Rectangular epithelial cells forming sheet-like tissues.
Studying Cells
- Robert Hooke described cells in 1665 using a microscope he designed.
- Antonie van Leeuwenhoek discovered bacteria, protists, blood cells, and sperm cells with his small lenses.
- Late 19th-century microscopes allowed biologists to study cells in detail.
Light Microscopes
- Light microscopes use lenses to magnify images of stained or living cells.
- Light passes through the specimen and lenses that refract the light to enlarge the view.
- Resolution power in magnification is limited to about 2000X.
- Various optical systems (bright-field, dark-field, phase contrast, fluorescence, confocal) enable different ways of visualizing living cells.
Electron Microscopes
- Electron microscopes study the ultra-structure of cells, achieving resolutions less than 1 nm.
- Energized electrons focused by electromagnets provide extremely detailed images.
- Types include transmission and scanning electron microscopes.
Biochemical and Genetic Methods
- Cell fractionation separates cell parts for study.
- Centrifugation separates cellular components.
- Differential centrifugation generates a series of pellets.
- Density gradient centrifugation further purifies components.
Prokaryotic and Eukaryotic Cells
-
Prokaryotic cells (bacteria and archaea) lack membrane-bound organelles.
-
DNA is located in a region called the nucleoid.
-
Eukaryotic cells are characterized by membrane-bound organelles.
- DNA is contained within the nucleus.
- Cytoplasm is the area outside the nucleus.
Organelles of Prokaryotic Cells
- DNA located in a nucleoid region instead of a nucleus.
- No membrane-bound organelles.
- Often have cell walls outside the plasma membrane.
- Some have flagella for movement.
- Ribosomes and storage granules are present.
Organelles of Eukaryotic Cells
- Contain a membrane-bound nucleus.
- Contains various specialized organelles performing specific functions.
- Examples of organelles and their functions are described in detail. (Nucleus, Ribosomes, Endoplasmic Reticulum, Golgi Complex, Lysosomes, Vacuoles, Peroxisomes , and Mitochondria / Chloroplasts. These will be listed below)
Nucleus
- The nucleus is the control center of the cell.
- Nuclear envelope separates nuclear contents from cytoplasm.
- Nuclear pores regulate materials between nucleoplasm and cytoplasm.
- Nuclear lamina helps organize DNA and regulates the cell cycle.
- DNA replicates during cell division.
- DNA's instructions are transcribed to mRNA and transported to the cytoplasm where proteins are synthesized.
- Chromatin is DNA associated with proteins.
- 46 chromosomes exist in a normal human cell (23 pairs).
- Nucleolus is responsible for rRNA synthesis. Ribosomes are assembled from rRNA and protein imported from the cytoplasm.
Ribosomes
- Ribosomes synthesize proteins.
- They are found free in cytoplasm or attached to membranes.
- Contain enzymes forming peptide bonds between amino acids.
- Ribosomes have a large and small subunit, assembling amino acids into polypeptides.
Endomembrane System
- A network of organelles exchanging materials through transport vesicles.
- Vesicles have membrane proteins that act as routing signals to their target organelles.
Endoplasmic Reticulum (ER)
- ER is a significant component of the cytoplasmic volume.
- Smooth ER synthesizes lipids, breaks down toxins, and might store Ca2+.
- Rough ER synthesizes secreted and membrane proteins.
Golgi Complex
- Stacks of flattened membranous sacs (cisternae).
- Processes, sorts modifications of proteins.
- Consists of cis (entry), trans (exit), and medial regions.
- Modifies and packages proteins for transport to destinations.
Lysosomes
- Small sacs of digestive enzymes in animal cells.
- Contain about 40 different digestive enzymes.
- Maintain an interior pH of around 5.
- Bud from Golgi complex.
- Primary lysosomes fuse with vesicles to form secondary lysosomes; involved in digestion.
Vacuoles
- Large, membrane-bound sacs. -Tonoplast is the vacuole's membrane. -Plant cells have central vacuoles crucial for growth and development.
- Play a significant role in growth and development. (in plant cells) -Plant vacuoles are like lysosomes breaking down cellular waste.
- Food vacuoles fuse with lysosomes to digest nutrients.
- Contractile vacuoles remove excess water from cells.
Peroxisomes
- Contain enzymes for hydrogen transfer.
- Break down fatty acids.
- Synthesize phospholipids.
- Degrade alcohol.
- Detoxify toxic compounds.
- Convert stored fats to sugars in plants.
Mitochondria and Chloroplasts
- Mitochondria and chloroplasts are energy-converting organelles.
- Convert energy from one form to another; often converting to ATP.
- Have their own ribosomes and DNA; (indicating an endosymbiotic origin).
- Mitochondria are involved in aerobic respiration which converts energy in food into ATP. Key reactions are described.
- Chloroplasts are the site of photosynthesis, converting light energy into ATP and glucose. Key components are described.
Cytoskeleton
- Consists of microtubules, microfilaments and intermediate filaments.
- Helps maintain cell shape, anchor organelles, sometimes enabling rapid cell movement.
Microtubules
- Rigid, hollow rods ~25 nm in diameter.
- Function in cytoskeleton structure.
- Support cellular movement (e.g., chromosomes).
- Transport intracellular materials.
- Microtubule-associated proteins (MAPs) control microtubule assembly and structure.
- Motor proteins (e.g., Kinesin, Dynein) use ATP for movement along microtubules.
Centrosomes and Centrioles
- Microtubule-organizing centers (MTOCs) in animal cells.
- Crucial for cell division. -Organize microtubules into a mitotic spindle for chromosome distribution during cell division.
Cilia and Flagella
- Hair-like structures involved in cellular movement.
- Aid in movement through watery environments.
- Cilia move fluids and particles; Flagella, often found on sperm, propel the cell.
- Contain a 9 + 2 arrangement of microtubules.
- Anchored by basal bodies (kinetosomes).
Microfilaments
- Flexible, solid fibers ~7 nm in diameter; made up of intertwined actin molecules.
- Important for support of cell structure.
- Form the cell cortex just beneath the plasma membrane.
- Involved in cell movement and muscle contraction.
- Actin filaments play roles in pseudopodia formation in amoeba-like cells. Contraction of muscle cells.
Intermediate Filaments
- Tough, flexible fibers ~10 nm in diameter.
- Provide mechanical strength and stabilize cell shape.
- Examples include (keratins, neurofilaments).
- Abnormal intermediate filaments can be linked to diseases.
Cell Coverings
- Glycocalyx surrounds many cells; important for cell recognition, contact, and adhesion in tissues.
- Extracellular matrix (ECM) in animal cells is made up of carbohydrates and proteins (e.g., collagen, fibronectins/integris), helping in attachment and tissue support.
- Plant cells have cell walls for support, made mainly of cellulose, with a primary cell wall for growth and secondary cell wall for rigidity.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
