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Questions and Answers
What is one of the primary functions of the cytoskeleton?
What is one of the primary functions of the cytoskeleton?
What are the three types of protein fibers found in the cytoskeleton?
What are the three types of protein fibers found in the cytoskeleton?
Which component of the cytoskeleton is primarily responsible for cellular movement?
Which component of the cytoskeleton is primarily responsible for cellular movement?
What is the approximate diameter of microfilaments?
What is the approximate diameter of microfilaments?
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What role do intermediate filaments play within a cell?
What role do intermediate filaments play within a cell?
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Which protein is microfilaments primarily composed of?
Which protein is microfilaments primarily composed of?
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How do microtubules contribute to cell shape?
How do microtubules contribute to cell shape?
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What structure anchors organelles and maintains the cell's shape?
What structure anchors organelles and maintains the cell's shape?
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What role do ribosomes play in the cell?
What role do ribosomes play in the cell?
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What are the two subunits that make up a ribosome called?
What are the two subunits that make up a ribosome called?
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Where do ribosomes receive their instructions for protein synthesis?
Where do ribosomes receive their instructions for protein synthesis?
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Which of the following cells is likely to have an abundance of ribosomes?
Which of the following cells is likely to have an abundance of ribosomes?
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In what form do ribosomes appear when viewed under an electron microscope?
In what form do ribosomes appear when viewed under an electron microscope?
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What is the significance of the ribosome's ability to assemble amino acids?
What is the significance of the ribosome's ability to assemble amino acids?
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What travels from the nucleus to the ribosomes to direct protein synthesis?
What travels from the nucleus to the ribosomes to direct protein synthesis?
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Why are ribosomes found in practically every cell?
Why are ribosomes found in practically every cell?
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What is the primary function of plasmodesmata in plant cells?
What is the primary function of plasmodesmata in plant cells?
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Which proteins are predominantly involved in forming tight junctions between animal cells?
Which proteins are predominantly involved in forming tight junctions between animal cells?
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Where are tight junctions most commonly found?
Where are tight junctions most commonly found?
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What structure in animal cells functions like spot welds to hold cells together?
What structure in animal cells functions like spot welds to hold cells together?
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What role do cadherins play in the formation of desmosomes?
What role do cadherins play in the formation of desmosomes?
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Which of the following statements about plasmodesmata is correct?
Which of the following statements about plasmodesmata is correct?
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What is a primary consequence of tight junction adhesion in epithelial tissues?
What is a primary consequence of tight junction adhesion in epithelial tissues?
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Which statement accurately describes the location and function of desmosomes?
Which statement accurately describes the location and function of desmosomes?
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What is the primary function of microtubules in a cell?
What is the primary function of microtubules in a cell?
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What is the diameter of microtubules?
What is the diameter of microtubules?
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Which proteins are the main building blocks of microtubules?
Which proteins are the main building blocks of microtubules?
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What structural differences exist between eukaryotic and prokaryotic flagella?
What structural differences exist between eukaryotic and prokaryotic flagella?
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What role do cilia serve when they extend along the plasma membrane?
What role do cilia serve when they extend along the plasma membrane?
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How quickly can microtubules disassemble and reform?
How quickly can microtubules disassemble and reform?
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Where is the microtubule-organizing center located in animal cells?
Where is the microtubule-organizing center located in animal cells?
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Which of the following statements about flagella is true?
Which of the following statements about flagella is true?
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What is the primary component that separates a prokaryotic cell's interior from its environment?
What is the primary component that separates a prokaryotic cell's interior from its environment?
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Where is prokaryotic DNA primarily localized within the cell?
Where is prokaryotic DNA primarily localized within the cell?
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What unique structural component do most prokaryotes possess that aids in maintenance of shape and protection?
What unique structural component do most prokaryotes possess that aids in maintenance of shape and protection?
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What is the function of flagella in prokaryotic cells?
What is the function of flagella in prokaryotic cells?
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Which of the following structures is NOT found in all prokaryotic cells?
Which of the following structures is NOT found in all prokaryotic cells?
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What role do pili play in prokaryotic cells?
What role do pili play in prokaryotic cells?
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How do prokaryotic cells compare in size to eukaryotic cells?
How do prokaryotic cells compare in size to eukaryotic cells?
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What feature of some prokaryotes helps them attach to surfaces in their environment?
What feature of some prokaryotes helps them attach to surfaces in their environment?
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Study Notes
Prokaryotic Cells
- Prokaryotic cells are single-celled organisms lacking a nucleus or any membrane-bound organelles.
- Common components of all cells include a plasma membrane, cytoplasm (jelly-like substance within the cell), DNA, and ribosomes.
- Prokaryotic DNA is located in the nucleoid, a central region of the cell.
- Prokaryotic cell wall is composed of peptidoglycan, providing extra protection, maintaining cell shape, and preventing dehydration.
- Capsule is a polysaccharide layer found in some prokaryotes, allowing them to attach to surfaces.
- Flagella are used for locomotion.
- Pili exchange genetic material during conjugation.
- Fimbriae facilitate bacterial attachment to host cells.
- Prokaryotic cells are significantly smaller than eukaryotic cells, ranging from 0.1 to 5.0 μm in diameter.
Ribosomes in Prokaryotes
- Ribosomes are responsible for protein synthesis.
- Ribosomes appear as clusters (polyribosomes) or individual dots within the cytoplasm.
- Ribosomes are composed of two subunits: a large subunit and a small subunit.
- Ribosomes receive instructions for protein synthesis from mRNA, which is transcribed from DNA in the nucleus.
- Ribosomes are crucial for all cells, as they produce essential proteins like enzymes, hormones, antibodies, pigments, and structural components.
Cytoskeleton in Prokaryotes
- Cytoskeleton is a network of protein fibers responsible for maintaining cell shape, anchoring organelles, facilitating movement of cytoplasm and vesicles, and enabling cellular movement.
- Three types of protein fibers make up the cytoskeleton: microfilaments, intermediate filaments, and microtubules.
Microfilaments
- Microfilaments are the narrowest cytoskeletal fibers (7 nm diameter).
- Microfilaments are composed of two intertwined strands of actin, a globular protein, also known as actin filaments.
- Microfilaments facilitate cellular movement.
Microtubules
- Microtubules are hollow tubes (25 nm diameter).
- Microtubules are made of polymerized dimers of α-tubulin and β-tubulin.
- Microtubules resist compression, serve as tracks for vesicle movement, and pull replicated chromosomes during cell division.
- Microtubules are components of flagella, cilia, and centrioles.
- Centrosome is the microtubule-organizing center in animal cells.
Flagella and Cilia in Prokaryotes
- Flagella are long, hair-like structures extending from the plasma membrane, used for cell movement.
- Cilia are numerous, short, hair-like structures extending from the plasma membrane, also used for cell movement.
Plasmodesmata in Plants
- Plasmodesmata are channels connecting the cell walls of neighboring plant cells, allowing the exchange of materials between their cytoplasm.
- Plasmodesmata facilitate the transport of water and nutrients throughout the plant.
Tight Junctions in Animals
- Tight junctions are watertight seals between adjacent animal cells.
- Tight junctions are formed by proteins like claudins and occludins, preventing leakage between cells.
- Tight junctions are prevalent in epithelial tissues lining internal organs and cavities.
Desmosomes in Animals
- Desmosomes act as spot welds between adjacent epithelial cells.
- Desmosomes are formed by cadherins, which connect to intermediate filaments, holding cells together in sheet-like formations.
- Desmosomes are important in tissues that stretch, like skin, heart, and muscles.
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Description
This quiz covers essential aspects of prokaryotic cells, including their structure and function. Key components like the plasma membrane, ribosomes, and genetic material are discussed, providing a comprehensive look at these single-celled organisms. Test your knowledge on the unique features of prokaryotic cells and their significance in biology.
