Cell Theory and Types of Cells
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Questions and Answers

Which of the following statements accurately describes the function of ribosomes within eukaryotic cells?

  • Ribosomes regulate the passage of molecules in and out of the nucleus.
  • Ribosomes synthesize DNA for cell replication.
  • Ribosomes primarily produce energy for cellular functions.
  • Ribosomes are responsible for synthesizing proteins. (correct)

What is the primary distinguishing feature between prokaryotic and eukaryotic cells?

  • Eukaryotic cells contain ribosomes, while prokaryotic cells do not.
  • Eukaryotic cells possess a nuclear envelope surrounding their DNA. (correct)
  • Prokaryotic cells contain membrane-bound organelles distinct from eukaryotic cells.
  • Prokaryotic cells have a membrane-bound nucleus, whereas eukaryotic cells do not.

Which structure within a eukaryotic cell is primarily involved in gene expression and regulation?

  • Nucleus (correct)
  • Ribosomes
  • Nuclear lamina
  • Nucleolus

What role do nuclear pores play in the functioning of eukaryotic cells?

<p>They regulate the transport of molecules between the nucleus and the cytoplasm. (B)</p> Signup and view all the answers

How are chromatin and chromosomes related to each other during cell division?

<p>Chromatin tightly wraps into chromosomes, allowing for easier segregation during cell division. (A)</p> Signup and view all the answers

Which of the following correctly describes the endomembrane system in eukaryotic cells?

<p>It includes various membranes that differ in structure and function to support different cellular jobs. (D)</p> Signup and view all the answers

What is the main function of the nucleolus found within the nucleus of eukaryotic cells?

<p>To produce ribosomal RNA (rRNA). (B)</p> Signup and view all the answers

How does the structure of the nuclear envelope contribute to its function?

<p>It consists of a double membrane, enhancing genetic material protection and molecule regulation. (B)</p> Signup and view all the answers

What is the primary function of the rough endoplasmic reticulum?

<p>Synthesize and transport secretory proteins (B)</p> Signup and view all the answers

Which component of the endomembrane system is directly involved in the sorting and shipping of proteins?

<p>Golgi apparatus (B)</p> Signup and view all the answers

What distinguishes the smooth endoplasmic reticulum from the rough endoplasmic reticulum?

<p>Absence of ribosomes (D)</p> Signup and view all the answers

In the context of the endomembrane system, what role do transport vesicles play?

<p>Transfer membrane and contents between compartments (D)</p> Signup and view all the answers

What is a notable feature of the Golgi apparatus that aids in the sorting of products?

<p>The addition of molecular ID tags such as phosphate groups (B)</p> Signup and view all the answers

Which option correctly describes the relationship between the nuclear envelope and the endoplasmic reticulum?

<p>The nuclear envelope is confluent with the rough endoplasmic reticulum. (D)</p> Signup and view all the answers

What specific function does the smooth endoplasmic reticulum perform in liver cells?

<p>Break down toxins and drugs (B)</p> Signup and view all the answers

Where does the Golgi apparatus receive materials from?

<p>From the rough endoplasmic reticulum (B)</p> Signup and view all the answers

What is the structure of the Golgi apparatus commonly described as?

<p>Stacked pancakes (B)</p> Signup and view all the answers

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

<p>To protect and support the plant cell (A)</p> Signup and view all the answers

Which component is found between the primary cell wall and the plasma membrane in mature plant cells?

<p>Secondary cell wall (D)</p> Signup and view all the answers

What role do plasmodesmata play in plant cells?

<p>Facilitate communication and transport between adjacent cells (D)</p> Signup and view all the answers

What is the characteristic structure of the primary cell wall during the early stages of plant growth?

<p>Thin and flexible (B)</p> Signup and view all the answers

Which polysaccharide is primarily found in the middle lamella of plant cells?

<p>Pectin (D)</p> Signup and view all the answers

What happens to the primary cell wall as the plant cell matures?

<p>It hardens as stronger materials are added (C)</p> Signup and view all the answers

Which of the following correctly describes the relationship between the primary and secondary cell walls?

<p>The secondary wall is added to the interior of the primary wall (B)</p> Signup and view all the answers

Which function is NOT associated with peroxisomes?

<p>Breaking down carbohydrates for energy (C)</p> Signup and view all the answers

What is the primary role of microtubules in the cytoskeleton?

<p>Separating chromosomes during cell division (A)</p> Signup and view all the answers

Which characteristic distinguishes intermediate filaments from microfilaments and microtubules?

<p>They provide a more permanent framework within the cell. (B)</p> Signup and view all the answers

What distinguishes eukaryotic cilia and flagella from each other?

<p>Cilia move in a whip-like manner, while flagella move in a wave-like motion. (C)</p> Signup and view all the answers

Which statement accurately describes the composition of microfilaments?

<p>They consist of actin protein in a double twisted chain. (D)</p> Signup and view all the answers

What is the main function of the cytoskeleton?

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

How do peroxisomes differ from mitochondria?

<p>Peroxisomes detoxify harmful substances while mitochondria primarily generate energy. (A)</p> Signup and view all the answers

Which structure anchors eukaryotic cilia and flagella to the cell?

<p>Basal body (D)</p> Signup and view all the answers

The stroma is primarily associated with which cellular structure?

<p>Thylakoids (A)</p> Signup and view all the answers

What role does catalase play in peroxisomes?

<p>It converts hydrogen peroxide into water and oxygen. (D)</p> Signup and view all the answers

What is the primary function of lysosomes in animal cells?

<p>Hydrolyze food and damaged cell parts (C)</p> Signup and view all the answers

Which statement about mitochondria is accurate?

<p>Mitochondria generate ATP through cellular respiration (C)</p> Signup and view all the answers

What is autophagy in the context of lysosomes?

<p>The massive rupture of lysosomes leading to cell self-digestion (A)</p> Signup and view all the answers

What is the role of the contractile vacuoles in freshwater protists?

<p>Pump excess water out of the cell (C)</p> Signup and view all the answers

How does the internal structure of chloroplasts facilitate photosynthesis?

<p>The stroma provides a site for sugar synthesis, while granum contains pigments (C)</p> Signup and view all the answers

What is a significant consequence of lysosome rupture in a cell?

<p>It triggers apoptosis or controlled cell death (C)</p> Signup and view all the answers

What indicates that lysosomal enzymes operate optimally at a specific pH level?

<p>They are inactive at neutral pH (D)</p> Signup and view all the answers

Which cellular structure is involved in both energy production and growth?

<p>Chloroplast (B)</p> Signup and view all the answers

What feature differentiates vacuoles from lysosomes?

<p>Vacuoles store nutrients, whereas lysosomes digest them (A)</p> Signup and view all the answers

What is a key characteristic of mitochondria?

<p>They have their own DNA and ribosomes (D)</p> Signup and view all the answers

Flashcards

Endomembrane System

A network of membranes and organelles within a eukaryotic cell, working together to modify, package, and transport proteins and lipids.

Endoplasmic Reticulum (ER)

A network of interconnected membranes in the cytoplasm of a eukaryotic cell, important in protein and lipid synthesis.

Rough ER

Part of the ER studded with ribosomes, involved in protein synthesis and modification.

Smooth ER

Part of the ER without ribosomes, involved in lipid synthesis and detoxification.

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Golgi Apparatus

A stack of flattened sacs involved in modifying, sorting, and packaging proteins and lipids for secretion or transport to other organelles.

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Transport Vesicles

Small sacs of membrane that transport materials between organelles.

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Lysosomes

Membrane-bound organelles containing digestive enzymes, breaking down waste and cellular debris.

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Nuclear Envelope

A double membrane that encloses the nucleus, separating its contents from the cytoplasm. 

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Cis face of Golgi

The receiving side of the Golgi, where transport vesicles arrive from the ER.

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Trans face of Golgi

The shipping side of the Golgi, where modified proteins and lipids are packaged into vesicles.

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Lysosomes

Membrane-bound sacs containing hydrolytic enzymes, used for digestion and recycling within animal cells

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Lysosome function

Hydrolyze (break down) food, whole cells, and damaged cell parts; crucial for proper cell maintenance.

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Autophagy

Self-destruction of a cell by massive lysosome rupture leading to the breakdown of cellular components.

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Mitochondria

Double-membraned organelles that generate ATP (energy) through cellular respiration.

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Mitochondrial Structure

Inner membrane (cristae) folded to increase surface area for chemical reactions; Matrix inside holds DNA, ribosomes, and respiration enzymes

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Chloroplast

Plastids found in plant cells, responsible for photosynthesis, converting sunlight to chemical energy.

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Chloroplast structure

Double membranes enclose stroma, a fluid-filled space; Grana stack inside increase photosynthesis efficiency.

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Cellular Respiration

Process in mitochondria where sugars, fats, and other fuels are broken down to produce ATP, the energy currency of the cell.

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Vacuole

Membrane-bound sacs with various functions, including storing food, water, and waste products.

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Endomembrane System

A group of organelles (e.g., ER, Golgi, lysosomes, vacuoles) working together to modify, package, and transport cellular products.

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Plant Cell Wall

A rigid layer outside the plasma membrane in plant cells, providing support and protection.

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Primary Cell Wall

Thin, flexible wall in young plant cells, enabling growth.

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Secondary Cell Wall

Stronger wall layer formed inside the primary wall in mature plant cells, contributing to strength and structure.

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Middle Lamella

Sticky layer between the cell walls of adjacent plant cells, holding them together.

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Plasmodesmata

Channels in plant cell walls that connect the cytoplasm of adjacent cells, facilitating communication and transport.

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Cellulose Microfibrils

Strong, fibrous components of the plant cell wall.

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Plant Cell Structure

Plant cells have a cell wall, a primary wall, a secondary wall, and middle lamella, all contributing to structural integrity and support. Plasmodesmata connect adjacent cells.

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Grana

Stacks of thylakoid sacs in chloroplasts.

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Peroxisomes

Organelles that break down fatty acids and detoxify harmful substances.

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Cytoskeleton

Network of protein fibers that maintains cell shape and support.

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Microtubules

Hollow tubes made of tubulin, part of the cytoskeleton.

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Actin Microfilaments

Thin protein fibers that contribute to cell shape and movement.

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Intermediate Filaments

Cytoskeletal fibers that maintain cell shape and anchor organelles.

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Thylakoid Space

The space inside a thylakoid sac in chloroplasts.

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Catalase

Enzyme that converts hydrogen peroxide to water and oxygen.

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Cilia and Flagella

Hair-like extensions from cell surface involved in movement.

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Basal Body

Structure anchoring cilia or flagella to the cell, similar to a centriole.

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Cell Theory

All living things are made of cells, cells are the basic unit of structure and function, and cells arise from pre-existing cells.

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Prokaryotic Cell

A type of cell that lacks a nucleus and membrane-bound organelles, found in bacteria.

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Eukaryotic Cell

A type of cell that contains a nucleus and membrane-bound organelles, found in plants, animals, fungi, and protists.

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Nuclear Envelope

The double membrane surrounding the nucleus, containing nuclear pores for regulating passage of molecules.

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Ribosomes

Cellular structures that synthesize proteins, found free in the cytoplasm or attached to the endoplasmic reticulum.

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Cytoplasm

The region within a cell that lies outside the nucleus but inside the plasma membrane; contains cytosol and organelles.

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DNA

The molecule containing the genetic instructions for building and operating the cell.

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Endomembrane System

A network of membranes within a eukaryotic cell that modifies, packages, and transports proteins and lipids.

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Study Notes

Cell Theory

  • Cells are the fundamental units of structure and function in living things.
  • All living things are composed of cells.
  • Cells arise from pre-existing cells.

All Cells

  • Surrounded by a plasma (cell) membrane.
  • Contain cytosol (a semi-fluid substance within the membrane).
  • Contain organelles (structures with specific functions).
  • Contain DNA (deoxyribonucleic acid).
  • Contain ribosomes (responsible for protein synthesis).

Prokaryotic Cells (Bacteria)

  • Lack a nucleus.
  • Lack membrane-bound organelles.
  • Have DNA in the nucleoid region.

Eukaryotic Cells (Plants, Animals, Fungi, Protists)

  • Have a nucleus enclosed by a nuclear envelope.
  • Contain membrane-bound organelles.
  • DNA is contained within the nucleus.

Nucleus and Nuclear Envelope

  • Contains genes, including additional genes in mitochondria and chloroplasts.
  • Surrounded by a double membrane (separated by 20-40 nm space).
  • Contains nuclear pores lined by proteins (the nuclear pore complex), regulating the passage of molecules.
  • The nuclear side of the envelope is lined with a network of protein filaments (nuclear lamina) maintaining its shape.
  • Contains chromatin (DNA and histone proteins).
  • Chromatin condenses to form chromosomes during cell division.
  • The nucleolus is a densely stained, ribosome-producing region within the nucleus.

Ribosomes

  • Synthesize proteins.
  • Composed of proteins and RNA (rRNA).
  • Can be free in the cytosol or bound to the rough endoplasmic reticulum (ER) or nuclear envelope.
  • Free ribosomes make proteins for the cytosol.
  • Bound ribosomes make proteins for cell membranes or export.

Endomembrane System

  • Many membranes in eukaryotic cells are part of the endomembrane system.
  • Components of this system include the nuclear envelope, endoplasmic reticulum (ER), Golgi apparatus, lysosomes, vacuoles, and the plasma membrane.
  • These components are directly continuous or connected via transfer of membrane sacs (vesicles).

Endoplasmic Reticulum (ER)

  • Membranous tubules forming internal fluid-filled spaces (cisternae).
  • Continuous with nuclear envelope.
  • Rough ER (with ribosomes): Synthesizes proteins, modifies proteins, and inserts proteins into membranes.
  • Smooth ER (lacks ribosomes): Synthesizes lipids, metabolizes carbohydrates, detoxifies poisons, and stores calcium ions.

Golgi Apparatus

  • Flattened membranous sacs (cisternae).
  • Has cis (receiving) and trans (shipping) faces.
  • Modifies, sorts, packages, and ships proteins.

Lysosomes

  • Membrane-bound sacs containing hydrolytic (digestive) enzymes.
  • Breakdown of food, cellular debris, and damaged cell parts.
  • Maintain a low internal pH; preventing accidental "self destruction" if a lysosome ruptures.
  • Involved in autophagy (recycling of cell's organelles and macromolecules)

Vacuoles

  • Membrane-bound sacs with varied functions.
  • Food vacuoles (formed by phagocytosis).
  • Contractile vacuoles (in protists, pump excess water).
  • Large central vacuole (in plant cells): Stockpile proteins or inorganic ions; dispose of metabolic byproducts; storing defensive compounds.

Mitochondria

  • Not part of the endomembrane system.
  • Double membrane (outer and inner).
  • Inner membrane folds (cristae) increase surface area for chemical reactions.
  • Fluid-filled space inside inner membrane (matrix).
  • Contains DNA, ribosomes, enzymes for cellular respiration (breaks down sugars, fats, and other fuels in the presence of oxygen).
  • Site of cellular respiration, generates ATP (adenosine triphosphate).

Chloroplasts

  • Not part of the endomembrane system; found in plants and algae.
  • Site of photosynthesis.
  • Convert solar energy to chemical energy and synthesize sugars from CO2 and H2O.
  • Double membrane (outer and inner).
  • Contains thylakoid sacs in stacks (grana), surrounded by stroma.
  • Site of photosynthesis for plants.

Peroxisomes

  • Single membrane; built from proteins and lipids in cytosol.
  • Involved in metabolism (e.g., breakdown of fatty acids, detoxification).
  • Contain enzymes that transfer hydrogen to oxygen, producing hydrogen peroxide (H2O2), and contain the enzyme catalase which converts H2O2 to H2O and O2.

Cytoskeleton

  • Network of fibers extending throughout the cytoplasm.
  • Provides mechanical support and maintains cell shape.
  • Anchors organelles.
  • Dynamic; structure changes over time.
  • Three main types: microtubules, microfilaments, and intermediate filaments.

Microtubules

  • Hollow tubes made of tubulin protein subunits.
  • Support, motility (cilia, flagella), and chromosome movements.
  • Movement inside cell of organelles and vesicles.

Microfilaments

  • Two intertwined actin strands.
  • Cell shape maintenance and cell motility (e.g., muscle contraction, ameboid movement).

Intermediate Filaments

  • Fibrous proteins.
  • Cell shape maintenance and anchors nucleus and organelles.

Animal Cell Extracellular Matrix (ECM)

  • Outside cell membrane; composed of glycoproteins (mostly collagen).
  • Strengthen tissues and serve as channels for transmitting external stimuli.
  • Three types of intercellular links: tight junctions, desmosomes, and gap junctions.

Plant Cell Walls

  • Found in plants, fungi, and some prokaryotes.
  • Made of cellulose and other polysaccharides.
  • Protects, supports, and maintains shape.
  • Primary cell wall is thin, flexible, and formed in young plants.
  • Middle lamella is a layer between cell walls of adjacent cells/pectins(thick polysaccharide).
  • Secondary cell wall may be formed in older plants and placed between the primary wall and plasma membrane. (several laminated layers).
  • Plasmodesmata (channels through walls) allows cytosol to pass between adjacent plant cells.

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