Cytoskeleton 2 Microtubules & Intermediate Filaments
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Questions and Answers

What is the tubulin subunit composed of in microtubules?

  • An alpha-tubulin and a beta-tubulin (correct)
  • An alpha-tubulin and a gamma-tubulin
  • Two alpha-tubulins
  • Two beta-tubulins

    • What happens to the GTP molecule bound to alpha-tubulin in microtubules?

  • It is trapped and never hydrolyzed or exchanged (correct)
  • It is exchanged with GDP during polymerization
  • It is hydrolyzed during depolymerization
  • It is involved in recruiting microtubule-associated proteins

    • What is the consequence of GDP exchange with GTP in microtubules during depolymerization?

  • Microtubules shrink
  • Microtubules grow (correct)
  • New microtubules are nucleated
  • Microtubules stay stable

    • Which structural component forms the hollow cylindrical structure of microtubules?

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

    What is the primary function of microtubules in cells?

    <p>Provide mechanical stability to the cell</p> Signup and view all the answers

    How are microtubules affected by drugs like colchicine or paclitaxel?

    <p>Inducing depolymerization</p> Signup and view all the answers

    What is dynamic instability in microtubules?

    <p>The coexistence of assembly and disassembly at the ends of a microtubule</p> Signup and view all the answers

    What happens when GTP hydrolysis proceeds more rapidly than the addition of new subunits to a microtubule?

    <p>The microtubule begins to depolymerize (shrink)</p> Signup and view all the answers

    What is the role of kinesin in relation to microtubules?

    <p>Travels towards the (+) end of microtubules</p> Signup and view all the answers

    Which statement about dynein is correct?

    <p>Composed of two identical heavy chains and transports cargo towards the (-) end of microtubules</p> Signup and view all the answers

    Which activity occurs in the globular head domains of kinesin?

    <p>ATP hydrolysis</p> Signup and view all the answers

    What is the clinical relevance of microtubules dynamic instability?

    <p>Regulating cell growth, movement, and cell signaling events</p> Signup and view all the answers

    What is the major structural role of microtubules in eukaryotic cells?

    <p>Formation of cilia and flagella</p> Signup and view all the answers

    What is responsible for aligning and segregating chromosomes during cell division?

    <p>Astral microtubuli</p> Signup and view all the answers

    How do cilia and flagella move?

    <p>Dynein motor proteins bend microtubules</p> Signup and view all the answers

    What is the difference between prokaryotic and eukaryotic flagella?

    <p>Prokaryotic flagella are structurally different and lack microtubule-based structures</p> Signup and view all the answers

    What structures are responsible for moving cells in an aqueous environment?

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

    What can cilia do in terms of moving fluid around a cell?

    <p>Move fluid around the cell</p> Signup and view all the answers

    What is the primary function of intermediate filaments in cells?

    <p>Strengthening cells and epithelia</p> Signup and view all the answers

    Which drug binds irreversibly to microtubules and spindle proteins, interfering with the formation of the mitotic spindle in tumor cells?

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

    What is the role of colchicine in familial Shar-pei fever treatment?

    <p>Prevents polymerization of microtubules</p> Signup and view all the answers

    Which structure forms a protective cage for the cell's DNA by lining the inner face of the nuclear envelope?

    <p>Intermediate filaments</p> Signup and view all the answers

    What effect does paclitaxel have on microtubules in cells?

    <p>Increases dynamic nature</p> Signup and view all the answers

    Which type of cells do intermediate filaments help extend long and robust axons?

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

    What is the major microtubule organizing center (MTOC) in animal cells?

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

    Which cellular structure is composed of two cylinders called centrioles?

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

    What is the function of MAPs (Microtubule-Associated Proteins) in cells?

    <p>Vesicle and organelle movement</p> Signup and view all the answers

    What does the term 'cell polarity' refer to?

    <p>Spatial differences in shape, structure, and function within a cell</p> Signup and view all the answers

    Where do microtubules originate from in a cell?

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

    How many amino acids long are each of the closely related globular proteins forming the tubulin subunit in microtubules?

    <p>445-450 amino acids</p> Signup and view all the answers

    What happens to the GTP molecule bound to beta-tubulin during microtubule depolymerization?

    <p>It is exchanged to GDP</p> Signup and view all the answers

    How are microtubules formed structurally?

    <p>Hollow cylindrical structures</p> Signup and view all the answers

    What is the process called when microtubules grow by adding new subunits?

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

    Which component of the tubulin heterodimer has a binding site for GTP that is not hydrolyzed or exchanged?

    <p>Alpha-tubulin</p> Signup and view all the answers

    What is the structural arrangement of alpha-beta tubulin heterodimers in microtubules?

    <p>Head to tail</p> Signup and view all the answers

    What is the primary function of intermediate filaments in cells?

    <p>Provide mechanical stability to cells and tissues</p> Signup and view all the answers

    How does vincristine affect tumor cells?

    <p>Arrests tumor cells in metaphase</p> Signup and view all the answers

    Which component forms the hollow cylindrical structure of microtubules?

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

    What is the role of colchicine in relation to microtubules?

    <p>Prevents polymerization of microtubules</p> Signup and view all the answers

    What effect does paclitaxel have on microtubules in cells?

    <p>Increases dynamic nature of microtubules</p> Signup and view all the answers

    What is the major structural role of microtubules in eukaryotic cells?

    <p>Assist in chromosome alignment during division</p> Signup and view all the answers

    What is the main structural role of microtubules in eukaryotic cells?

    <p>Providing specialized motility structures like cilia</p> Signup and view all the answers

    In prokaryotes, how do flagella structurally differ from eukaryotic flagella?

    <p>Prokaryotic flagella do not contain any microtubule-based structures</p> Signup and view all the answers

    What is the role of the dynein motor proteins in cilia and flagella movement?

    <p>Allowing bending and generating force for movement</p> Signup and view all the answers

    Which cells use flagella to move in an aqueous environment?

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

    What occurs when a cell divides concerning microtubules?

    <p>Microtubules rearrange to form a bipolar mitotic spindle</p> Signup and view all the answers

    What is the function of cilia concerning fluid movement around a cell?

    <p>Moving fluid around the cell</p> Signup and view all the answers

    What is the primary role of microtubules in transporting intracellular cargoes?

    <p>Transporting vesicles, organelles, and protein complexes</p> Signup and view all the answers

    Which cellular structure is considered as the major microtubule organizing center (MTOC) in animal cells?

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

    What are centrioles and where are they typically located in animal cells?

    <p>Tiny cylindrical structures near the nucleus, participating in spindle fiber development</p> Signup and view all the answers

    What is the term for spatial differences in shape, structure, and function within a cell?

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

    Which cellular components read Microtubule-Associated Proteins (MAPs) to facilitate organelle and vesicle movement?

    <p>Microtubule motors</p> Signup and view all the answers

    Where do microtubules originate from within a cell?

    <p>Microtubule organizing center (MTOC)</p> Signup and view all the answers

    What is the central building block of intermediate filaments?

    <p>Coiled-coil dimer</p> Signup and view all the answers

    Which family of intermediate filaments is primarily produced by keratinocytes in the epidermis?

    <p>Epithelial keratin filaments</p> Signup and view all the answers

    What is the clinical utility of the diversity of keratins in epithelial cancers?

    <p>Guiding treatment choices</p> Signup and view all the answers

    Which intermediate filament type provides mechanical stability to the cell nucleus?

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

    What is the primary function of neurofilaments in cells?

    <p>Contribute to axonal growth and stability</p> Signup and view all the answers

    Which type of intermediate filament is primarily responsible for maintaining cell shape and integrity?

    <p>Vimentin filaments</p> Signup and view all the answers

    What does dynamic instability in microtubules refer to?

    <p>The simultaneous assembly and disassembly at the microtubule ends</p> Signup and view all the answers

    What happens if GTP hydrolysis occurs more rapidly than the addition of new subunits to a microtubule?

    <p>The microtubule starts to depolymerize</p> Signup and view all the answers

    Which domain of tubulin dimer is responsible for GTP hydrolysis in microtubules?

    <p>Beta-subunit</p> Signup and view all the answers

    What is the structural plasticity and dynamics of microtubules dependent on?

    <p>GTP-binding domain of beta-tubulin</p> Signup and view all the answers

    Which protein travels towards the positive end of the microtubule?

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

    What is the clinical relevance of the dynamic instability of microtubules?

    <p>Regulating cell growth and movement</p> Signup and view all the answers

    What is the function of paclitaxel (Taxol) in anticancer chemotherapy?

    <p>Prevents progression of mitotic cells to G1 phase</p> Signup and view all the answers

    Which drug binds irreversibly to microtubules and spindle proteins, interfering with mitotic spindle formation in tumor cells?

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

    How does colchicine aid in familial Shar-pei fever treatment?

    <p>Prevents polymerization of microtubules</p> Signup and view all the answers

    Which statement accurately describes intermediate filaments?

    <p>Have a polarity (+ or - end)</p> Signup and view all the answers

    What is the role of intermediate filaments in cell structure?

    <p>Strengthen cells and epithelia</p> Signup and view all the answers

    Which protein forms a protective cage for a cell's DNA by lining the nuclear envelope?

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

    What cellular component is responsible for the selective stabilization of microtubules, allowing for cell polarization?

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

    What is the major microtubule organizing center (MTOC) in animal cells?

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

    What is the function of microtubule motors in relation to MAPs?

    <p>Read and transport organelles based on MAPs</p> Signup and view all the answers

    What is the specific function of centrioles in animal cells?

    <p>Developing spindle fibers during cell division</p> Signup and view all the answers

    Which cellular structure is composed of two cylinders called centrioles?

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

    What is the primary role of MAPs in intracellular transport?

    <p>Move vesicles and organelles along microtubules</p> Signup and view all the answers

    What is the structural role of microtubules in cilia and flagella?

    <p>Serve as the major component responsible for motility structures</p> Signup and view all the answers

    What is the primary function of the dynein motor proteins in cilium and flagellum movement?

    <p>Generating force for bending microtubules</p> Signup and view all the answers

    How do prokaryotic flagella differ structurally from eukaryotic flagella?

    <p>Completely different structure from eukaryotic flagella</p> Signup and view all the answers

    What is the main function of epithelial keratin filaments in cells?

    <p>Anchor epithelial cells via desmosomes/hemidesmosomes</p> Signup and view all the answers

    What clinical utility can be derived from the diversity of keratins in epithelial cancers?

    <p>Diagnosis of the epithelial tissue in which cancer originated</p> Signup and view all the answers

    Which type of intermediate filaments is essential for scaffold function in sarcomeres of skeletal and cardiac muscle?

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

    What is the primary role of neurofilaments within cells?

    <p>Participating in axonal growth in neurons</p> Signup and view all the answers

    In what specific diseases do mutations in keratin genes lead to disruption of the normal keratin network in skin cells?

    <p>Blistering diseases like epidermolysis bullosa simplex (EBS)</p> Signup and view all the answers

    What is the major structural role of lamin within a cell?

    <p>Mechanical stability of the cell nucleus</p> Signup and view all the answers

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