Non-Membranous Organelles Quiz
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Questions and Answers

What is one of the primary functions of microtubules?

  • Translocation of organelles
  • Formation of the contractile ring during mitosis
  • Muscle contraction
  • Maintenance of cell shape (correct)

    • Which statement accurately describes actin filaments?

  • They are more rigid than microtubules.
  • They primarily bind to keratins in epithelial cells.
  • They are the largest component of the cytoskeletal system.
  • They are 6 nm in diameter and are dynamic. (correct)

    • Which type of filament is found predominantly in muscle cells?

  • Intermediate filaments
  • Neurofilaments
  • Actin filaments (correct)
  • Microtubules

    • What role do intermediate filaments play in the cell?

    <p>They provide mechanical support and stability.</p> Signup and view all the answers

    Which of the following is a characteristic of microtubules?

    <p>They are involved in forming the mitotic spindle.</p> Signup and view all the answers

    Which class of intermediate filaments is found in epithelial cells?

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

    What distinguishes intermediate filaments from microtubules and actin filaments?

    <p>They are stable and do not disassemble.</p> Signup and view all the answers

    Which of the following is NOT a function of actin filaments?

    <p>Formation of mitotic spindle</p> Signup and view all the answers

    Which of the following is NOT a component of the cytoskeleton?

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

    What is the diameter range of intermediate filaments?

    <p>8 to 10 nm</p> Signup and view all the answers

    How many protofilaments form the circumference of each microtubule wall?

    <p>13</p> Signup and view all the answers

    What is the primary function of microtubules in eukaryotic cells?

    <p>Providing rigidity and shape</p> Signup and view all the answers

    Which of the following best describes the structure of microtubules?

    <p>Hollow, rigid structures made of α and β tubulin</p> Signup and view all the answers

    Which of the following processes is associated with the dynamic nature of microtubules?

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

    What role do the microtubules play in cellular movement?

    <p>They help in the movements of organelles and vesicles.</p> Signup and view all the answers

    Which of the following best describes the function of the cytoskeleton?

    <p>Determines cell shape and allows for cell movement</p> Signup and view all the answers

    What is the primary role of intermediate filaments of keratins in skin epidermal cells?

    <p>To form large bundles that attach to cell junctions</p> Signup and view all the answers

    Which protein is considered an important vimentin-like protein found in muscle cells?

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

    What is the function of lamins in the nuclear envelope?

    <p>To regulate gene transcription</p> Signup and view all the answers

    What is the size of a functional ribosome?

    <p>20 × 30 nm</p> Signup and view all the answers

    Where are ribosomal proteins synthesized before they are assembled into ribosomes?

    <p>In cytoplasmic ribosomes</p> Signup and view all the answers

    What distinguishes free polyribosomes from bound polyribosomes?

    <p>Bound polyribosomes are attached to the endoplasmic reticulum</p> Signup and view all the answers

    What role do neurofilament proteins play in cells?

    <p>They are subunits of intermediate filaments in neurons</p> Signup and view all the answers

    What property makes polyribosomes basophilic in stained preparations of cells?

    <p>The numerous phosphate groups of RNA molecules</p> Signup and view all the answers

    What is the main role of proteasomes in the cell?

    <p>Degrade denatured or short-lived proteins</p> Signup and view all the answers

    Which structure is responsible for recognizing ubiquitinated proteins?

    <p>Regulatory particle of proteasome</p> Signup and view all the answers

    What is the composition of a centriole?

    <p>Nine triplets of microtubules</p> Signup and view all the answers

    Which of the following is NOT a function of the proteasome?

    <p>Synthesize secretory proteins</p> Signup and view all the answers

    During which phase of the cell cycle does the centrosome duplicate?

    <p>DNA replication</p> Signup and view all the answers

    Which of the following statements about the proteasome's structure is true?

    <p>It has a cylindrical shape with stacked rings of proteins</p> Signup and view all the answers

    What type of proteins do proteasomes primarily deal with?

    <p>Free proteins including denatured ones</p> Signup and view all the answers

    What happens to the centrosome during mitosis?

    <p>It divides into halves and organizes microtubules</p> Signup and view all the answers

    Study Notes

    Non-Membranous Organelles

    • Cytoskeleton: composed of microfilaments, intermediate filaments, and microtubules.
    • Microfilaments: 6 nm in diameter, responsible for cell shape, locomotion, organelle movement, and muscle contraction.
    • Microtubules: 25 nm in diameter, maintain cell shape, facilitate intracellular transport, and form structures like mitotic spindles, centrioles, basal bodies, and axoneme of cilia and flagella.
    • Intermediate filaments: 8-10 nm in diameter, stable and diverse, important for cell structure and function depending on cell type.
      • Keratins: found in epithelial cells, contribute to keratinization in skin.
      • Vimentin: found in mesenchymal cells, and desmin in muscle cells, and GFAP in astrocytes, supporting cells of the central nervous system.
      • Neurofilaments: found in neurons.
      • Lamins: found in the nuclei of all cells, help maintain nuclear shape and participate in gene transcription.
    • Ribosomes: 20 × 30 nm in size, essential for protein synthesis.
      • Made of two subunits: small and large, bound to mRNA.
      • Composed of rRNA and proteins.
      • Exist as free or bound polyribosomes.
      • Free polyribosomes: synthesize cytoplasmic proteins.
      • Bound polyribosomes: associated with ER, synthesize membrane proteins, lysosomal enzymes, and secretory proteins.
    • Proteasomes: cylindrical protein complexes that degrade denatured or nonfunctional proteins.
      • Recognize proteins marked with ubiquitin.
      • Unfold and degrade proteins in their core.
      • Play a role in protein quality control and preventing cellular damage.
    • Centrosomes: composed of two centrioles surrounded by pericentriolar matrix (PCM).
      • Centrioles are cylindrical with nine microtubule triplets.
      • Duplicate during DNA replication.
      • Organize microtubules during mitosis, forming the mitotic spindle.

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    Related Documents

    Non-Membranous Organelles Lecture 10 PDF

    Description

    Test your knowledge on non-membranous organelles including cytoskeleton components such as microfilaments, microtubules, and intermediate filaments. Understand their structures, functions, and importance in cellular behavior. This quiz will challenge your understanding of these critical cellular components.

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