Cell Organelles: Cytoskeleton Structure and Function
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Questions and Answers

What is the primary function of microtubules in the cytoskeleton?

  • Intracellular transportation (correct)
  • Muscle contraction
  • Providing structural support to the nucleus
  • Maintaining the shape of the cell
  • What is the diameter of intermediate filaments?

  • 10 nm (correct)
  • 50 nm
  • 25 nm
  • 5-9 nm
  • What type of protein subunits make up microfilaments?

  • Lamins
  • Keratins
  • Actin (correct)
  • Tubulin
  • What is the structural role of intermediate filaments in the cell?

    <p>Providing structural support to specific tissues</p> Signup and view all the answers

    What is the composition of microtubules?

    <p>Heterodimers of alpha and beta tubulin</p> Signup and view all the answers

    What is the function of motor proteins in the cytoskeleton?

    <p>Transporting materials and organelles</p> Signup and view all the answers

    What is the primary function of microfilaments in skeletal muscles?

    <p>To integrate with thick myosin filaments for contraction</p> Signup and view all the answers

    What is the characteristic feature of intermediate filaments in epithelial tissues?

    <p>They are composed of cytokeratins</p> Signup and view all the answers

    Which type of filament is involved in the movement of vesicles and granules in the cytoplasm?

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

    What is the role of microfilaments in the process of cytokinesis?

    <p>To form a 'purse-string' ring of filaments</p> Signup and view all the answers

    Which type of intermediate filament is characteristic of glial cells?

    <p>Glial Fibrillary Acidic Proteins (GFAP)</p> Signup and view all the answers

    What is the clinical significance of finding intermediate filaments from cell A in cell B?

    <p>It indicates the presence of a tumor</p> Signup and view all the answers

    What is the primary function of kinesins and dyneins in cells?

    <p>To facilitate the transport of organelles and vesicles</p> Signup and view all the answers

    What is the composition of the central sheath in cilia and flagella?

    <p>2 microtubules bound to peripheral microtubules by radial spoke proteins</p> Signup and view all the answers

    What is the function of centrioles in non-dividing cells?

    <p>To serve as a site for microtubule nucleation and organization</p> Signup and view all the answers

    What is the primary function of microtubules in the mitotic spindle?

    <p>To align and separate chromosomes during cell division</p> Signup and view all the answers

    What is the characteristic feature of microtubules in cilia and flagella?

    <p>9-double microtubules with dynein</p> Signup and view all the answers

    What is the function of radial spoke proteins in cilia and flagella?

    <p>To bind peripheral microtubules to the central sheath</p> Signup and view all the answers

    What is the characteristic of microfilaments?

    <p>They are composed of actin filaments and have structural roles</p> Signup and view all the answers

    What is the primary function of intermediate filaments?

    <p>To provide mechanical support and stability to the cell</p> Signup and view all the answers

    What is the characteristic of inclusions?

    <p>They are not considered organelles and are not enclosed by a membrane</p> Signup and view all the answers

    What are glycogen granules?

    <p>Aggregates of a carbohydrate polymer</p> Signup and view all the answers

    What is the characteristic of pigmented granules?

    <p>They are stable in non-dividing cells</p> Signup and view all the answers

    What are fat droplets?

    <p>Accumulations of lipid molecules</p> Signup and view all the answers

    What is the primary function of proteasomes in the cell?

    <p>To degrade non-functional polypeptides and denatured proteins</p> Signup and view all the answers

    What is required for the proteasome degradation function to occur?

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

    What is the outcome of proteasome degradation?

    <p>Release of resulting peptides that can be reused by the cell</p> Signup and view all the answers

    What is the primary function of peroxisomes?

    <p>Fatty acid oxidation</p> Signup and view all the answers

    How do proteins get internalized by peroxisomes?

    <p>Through a signal sequence</p> Signup and view all the answers

    What is a byproduct of peroxisomal oxidation reactions?

    <p>H2O2</p> Signup and view all the answers

    What is the role of catalase in peroxisomes?

    <p>To break down H2O2</p> Signup and view all the answers

    What is the role of peroxisomes in lipid metabolism?

    <p>To break down fatty acids</p> Signup and view all the answers

    What is the diameter of peroxisomes?

    <p>0.5 µm</p> Signup and view all the answers

    Where are peroxisomal enzymes synthesized?

    <p>In free cytosolic polyribosomes</p> Signup and view all the answers

    What is the main function of lysosomes in cellular processes?

    <p>To recycle old or damaged organelles and digest food particles</p> Signup and view all the answers

    What is the characteristic of proteasomes that distinguishes them from lysosomes?

    <p>Their non-membranous structure</p> Signup and view all the answers

    What is the fate of residual bodies in certain cell types?

    <p>They are converted into lipofuscin granules</p> Signup and view all the answers

    What is the function of hydrolytic enzymes in lysosomes?

    <p>To break down and digest bulk materials</p> Signup and view all the answers

    What is the characteristic of lysosomes in macrophages and neutrophils?

    <p>They are larger in diameter</p> Signup and view all the answers

    What is the result of the fusion of phagosomes and lysosomes?

    <p>The formation of secondary lysosomes</p> Signup and view all the answers

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