Questions and Answers
What is one of the primary functions of the cytoskeleton in eukaryotic cells?
Which component of the cytoskeleton is primarily responsible for facilitating movement within the cell?
How do bacterial and eukaryotic cytoskeletal fibers compare?
What role do motor proteins play in the cytoskeleton?
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Which of the following structures is NOT a major component of the cytoskeleton?
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What are the primary functions of actin microfilaments in cells?
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Which of the following motor proteins interacts with actin filaments to cause muscle contraction?
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How do microfilaments contribute to the movement of amoeboid cells?
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What is the structure of actin microfilaments?
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Which of the following is NOT a function of microfilaments?
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Study Notes
The Cytoskeleton
- The cytoskeleton is a network of protein filaments and tubules in the cytosol of eukaryotic cells.
- Bacterial cells also possess cytoskeletal fibers made from similar proteins.
Functions of the Cytoskeleton
- Provides mechanical support and maintains the three-dimensional shape of cells, crucial for animal cells that lack cell walls.
- Serves as a transportation system within cells, facilitating movement of organelles and structures.
- Aids in cell division and enables movement of cells or parts of cells.
- Connects cells to one another.
Structure of the Cytoskeleton
- Composed of three main components: microfilaments, intermediate filaments, and microtubules.
- Each component varies in protein type, diameter, and formation, contributing to its structure and function.
Motor Proteins
- Motor proteins use ATP to transport organelles along cytoskeletal filaments or to move the filaments themselves.
- Major classes include myosin, kinesin, and dynein.
Microfilaments (Actin Filaments)
- Comprised of thin rods about 7 nanometers in diameter, built from actin protein.
- Features plus and minus ends, forming a twisted double chain of actin subunits.
- Functions:
- Provides tensile strength and helps anchor cells together.
- Forms a microfilament network, supporting the cell's shape and contributing to the gel-like consistency of the cortex.
- In specialized cells, bundles of microfilaments increase surface area through structures like microvilli.
- Facilitates cell motility via interactions with myosin, essential for muscle contractions and amoeboid movement.
Intermediate Filaments
- Intermediate in size, approximately 10 nanometers in diameter, these filaments are made from various protein subunits like keratins.
- Functions:
- Reinforces cell shape and anchors organelles to maintain structural integrity.
- Provides tensile strength similar to microfilaments.
- Important for cell adhesion (e.g., desmosomes).
- Defects in keratin can lead to diseases like Epidermolysis Bullosa, resulting in skin fragility.
Microtubules
- Hollow rods measuring around 23 nanometers, constructed from tubulin protein dimers (α and β).
- Functions:
- Provide shape and support to the cell.
- Act as tracks for organelle movement guided by motor proteins kinesin and dynein.
- Involvement in chromosome separation during cell division.
- Create structures like cilia and flagella for cellular movement.
Cilia and Flagella
- Both are extensions containing microtubules, differing in length, number, and movement patterns.
- Cilia are numerous and used for moving fluids over cell surfaces; flagella are longer and used for propulsion.
- Cilia also serve as sensory antennas, signaling changes in environmental conditions to the cell.
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Description
Explore the essential role of the cytoskeleton in eukaryotic cells with this quiz based on BIO 102. Participants will gain insights into the complex network of proteins that supports cell structure and function. Test your knowledge and understanding of cellular biology concepts related to the cytoskeleton.
