Cell Division and Cytoskeleton Functions
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Cell Division and Cytoskeleton Functions

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Questions and Answers

What is the diameter of microtubules in a cell?

  • 8 nanometers
  • 25 nanometers (correct)
  • 40 nanometers
  • 10 nanometers

    • Which type of filament is exclusively found in animal cells?

  • Microtubules
  • Microfilaments
  • Intermediate filaments (correct)
  • Contractile fibers

    • What are the two primary components of tubulin?

  • Microfilaments and actin
  • Alpha and beta tubulin (correct)
  • Intermediate filaments and keratins
  • Centrioles and centrosomes

    • What function does the cytoskeleton serve in cellular movement?

    <p>Maintaining cell's shape</p> Signup and view all the answers

    What is the primary microtubule organizing center in a cell?

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

    How many protofilaments typically form a single microtubule in mammalian cells?

    <p>10 to 15</p> Signup and view all the answers

    Which of the following is a characteristic of microfilaments?

    <p>Diameter of approximately 8 nanometers</p> Signup and view all the answers

    What role do centrioles play in the organization of microtubules?

    <p>Organizing pericentriolar material to produce microtubules</p> Signup and view all the answers

    What is the primary role of the cytoskeleton in a cell?

    <p>To assist in cell division and maintain cell shape.</p> Signup and view all the answers

    Which filamentous structure is responsible for rapidly growing and shrinking?

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

    How many different protein subunits compose intermediate filaments in humans?

    <p>70</p> Signup and view all the answers

    What structural feature characterizes microtubules?

    <p>A hollow cylinder</p> Signup and view all the answers

    What is the composition of centrioles?

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

    What diameter do microfilaments share?

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

    What is the function of microtubule organizing centers (MTOCs) in cells?

    <p>To generate microtubules and organize them.</p> Signup and view all the answers

    What type of filaments are associated with muscle cells?

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

    What happens to the nuclear membrane during prophase?

    <p>It breaks down into small vesicles.</p> Signup and view all the answers

    Which role do kinetochore microtubules play in anaphase?

    <p>They shorten to draw chromosomes toward spindle poles.</p> Signup and view all the answers

    During which phase do chromosomes migrate to the equatorial plane?

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

    What key process is observed during anaphase?

    <p>Separation of sister chromatids.</p> Signup and view all the answers

    What is the function of the mitotic spindle checkpoint?

    <p>To assess spindle assembly correctness.</p> Signup and view all the answers

    Which complexes contribute to the exit from metaphase?

    <p>APC/C complex and cyclins A and B</p> Signup and view all the answers

    What characterizes telophase in the cell cycle?

    <p>Chromosomes arrive at cell poles.</p> Signup and view all the answers

    Which type of microtubule is responsible for positioning the spindle apparatus during mitosis?

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

    What is the primary purpose of somatic cell division in eukaryotes?

    <p>To ensure tissue growth and regeneration</p> Signup and view all the answers

    Which phase directly follows karyokinesis during mitosis?

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

    Which of the following accurately describes cyclin-dependent kinases (CDKs)?

    <p>They require cyclin proteins for kinase activity.</p> Signup and view all the answers

    What occurs during the prophase phase of mitosis?

    <p>Chromosomes condense into compact structures.</p> Signup and view all the answers

    Which kinase is primarily responsible for phosphorylating H1 histone during prophase?

    <p>Cdk1</p> Signup and view all the answers

    Which phase of mitosis is characterized as the separation phase?

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

    What role do Polo-like kinases and Aurora kinases play in mitosis?

    <p>They regulate phosphorylation and centrosome function.</p> Signup and view all the answers

    How are sister chromatids held together during prophase?

    <p>By cohesin proteins</p> Signup and view all the answers

    Study Notes

    Cell Division - Cytoskeleton

    • The cytoskeleton is composed of three filamentous structures: microtubules, microfilaments (actin filaments), and intermediate filaments.

    Cytoskeleton - Functions

    • Maintains cell shape and changes shape during movement (e.g., cell division, organelle migration, cell migration).
    • Positions organelles.
    • Resists deformation.
    • Transports intracellular cargo (e.g., vesicles) and assists in the transport of communication signals between cells.

    Microtubules

    • The largest type of filament, composed of tubulin protein.
    • Diameter is approximately 25 nanometers.
    • Tubulin is composed of α-tubulin and β-tubulin subunits assembled into linear protofilaments.
    • Microtubules can rapidly grow or shrink in size through polymerization and depolymerization, respectively.
    • The size depends on the number of tubulin molecules they contain.
    • A single microtubule contains 10 to 15 protofilaments (13 in mammalian cells).
    • They wind together to form a 24 nm wide hollow cylinder.

    Centrosome

    • In cells, the minus ends of microtubules are anchored in structures called microtubule-organizing centers (MTOCs).
    • The primary MTOC in a cell is the centrosome.
    • The centrosome consists of two centrioles.
    • The centrosome is duplicated during the S phase of the cell cycle.

    Centrioles

    • Occur as paired cylindrical organelles together with pericentriolar material (PCM) containing more than 100 different proteins.
    • Constructed of microtubules.
    • Organize the PCM to produce microtubules, including mitotic spindle fibers.

    Intermediate Filaments

    • Composed of different protein subunits (~70 in humans).
    • Diameter is approximately 10 nanometers.
    • Found only in animal cells.
    • Associated with specific cell types: neurofilaments in neurons, desmin filaments in muscle cells, and keratins in epithelial cells.

    Microfilaments

    • The smallest type of filament composed of the contractile protein actin.
    • Diameter is approximately 8 nanometers.
    • Particularly prevalent in muscle cells.

    Motor Proteins

    • Use energy derived from ATP hydrolysis to generate movement and force.
    • Involved in cell movement:
      • Kinesin moves along microtubules to pull organelles towards the cell membrane.
      • Dynein pulls cellular components inward (toward the nucleus) and works to slide microtubules.
      • Myosin interacts with actin to perform muscle contractions, and is involved in cytokinesis, endocytosis, and exocytosis.

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    Related Documents

    Lecture 7: Cytoskeleton PDF
    Lecture 7_II_Mitosis PDF

    Description

    This quiz covers the composition and functions of the cytoskeleton, including its three main filamentous structures: microtubules, microfilaments, and intermediate filaments. Explore how these components maintain cell shape, assist in cell movement, and facilitate intracellular transport.

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