Microtubules and Molecular Motors Quiz
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Questions and Answers

What is the thickness of microtubules?

  • 50 nm
  • 25 nm (correct)
  • 5 nm
  • 10 nm

    • What are microtubules composed of?

  • Subunits of DNA
  • Subunits of lipid molecules
  • Subunits of carbohydrates
  • Subunits of globular protein tubulin (correct)

    • How many protofilaments typically form a microtubule?

  • 20
  • 15
  • 13 (correct)
  • 10

    • Which type of tubulin is involved in polymerization and organization of microtubules in the cell?

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

    What gives the structure of a microtubule polarity?

    <p>The organization of subunits with a-tubulin exposed at one end and B-tubulin at the other end</p> Signup and view all the answers

    How many protofilaments contact laterally to form a microtubule?

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

    What type of tubulin binds GTP reversibly and can be hydrolyzed to GDP?

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

    What drives the polymerization and depolymerization of microtubules?

    <p>Hydrolysis of GTP on B-tubulin monomer</p> Signup and view all the answers

    What type of tubulin is exposed at the minus end of a microtubule?

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

    How does the length of microtubules change?

    <p>By adding or removing heterodimers</p> Signup and view all the answers

    What does the myosin head hydrolyze ATP into?

    <p>ADP and inorganic phosphate</p> Signup and view all the answers

    What happens when the myosin head binds to actin?

    <p>A cross-bridge is formed</p> Signup and view all the answers

    What is the role of kinesins and dyneins during interphase?

    <p>Transport and positioning of organelles and vesicles</p> Signup and view all the answers

    What is responsible for the movement of cilia and flagella?

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

    What is the result of myosin head hydrolyzing ATP?

    <p>Release of energy</p> Signup and view all the answers

    What occurs when the myosin head is in a low-energy configuration?

    <p>Myosin binding sites are exposed</p> Signup and view all the answers

    What moves towards the center of the sarcomere during muscle contraction?

    <p>Thin filament</p> Signup and view all the answers

    What is involved in the sliding of microtubules against each other?

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

    What is the role of dyneins during cell division?

    <p>Movement of centrosomes and chromosomes</p> Signup and view all the answers

    What is responsible for intracellular transport during interphase?

    <p>Kinesins and dyneins</p> Signup and view all the answers

    What is the process called when one end of a microtubule polymerises while the other end disassembles?

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

    Which structure serves as nucleation sites for microtubule assembly?

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

    What are the hair-like cell appendages formed by microtubules and surrounded by a membrane called?

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

    Which molecular motors move toward the plus end of microtubules?

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

    What is the role of basal bodies in cell structures?

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

    What is the term for the process of changing chemical energy into mechanical energy and transporting cell structures along microtubules?

    <p>Molecular motor activity</p> Signup and view all the answers

    What determines the rate of microtubule polymerisation?

    <p>Critical concentration of alpha-tubulin</p> Signup and view all the answers

    What type of movement do dyneins exhibit along microtubules?

    <p>Toward the minus end</p> Signup and view all the answers

    What is the term for the phase in which microtubules form in vitro?

    <p>Steady state phase</p> Signup and view all the answers

    Which motor movement consists of filament binding, conformational change, filament release, and conformational relaxation?

    <p>Molecular motor movement</p> Signup and view all the answers

    What gives the structure of a microtubule polarity?

    <p>a-tubulin exposed at one end and B-tubulin at the other end</p> Signup and view all the answers

    What type of tubulin binds GTP reversibly and can be hydrolyzed to GDP?

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

    How many protofilaments typically form a microtubule?

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

    What is the role of y-tubulin in microtubule organization?

    <p>It is involved in polymerization and organization of microtubules</p> Signup and view all the answers

    What is the term for the process of changing chemical energy into mechanical energy and transporting cell structures along microtubules?

    <p>Motor movement</p> Signup and view all the answers

    What drives the depolymerization of microtubules?

    <p>Hydrolysis of GTP on B-tubulin</p> Signup and view all the answers

    What is the term for the phase in which microtubules form in vitro?

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

    What are microtubules composed of?

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

    What occurs when the myosin head binds to actin?

    <p>Conformational change</p> Signup and view all the answers

    What is the thickness of microtubules?

    <p>25 nm</p> Signup and view all the answers

    What is the result of myosin head hydrolyzing ATP?

    <p>Formation of ADP and inorganic phosphate</p> Signup and view all the answers

    What occurs when the myosin head binds to actin?

    <p>Formation of a cross-bridge</p> Signup and view all the answers

    Which motor movement consists of filament binding, conformational change, filament release, and conformational relaxation?

    <p>Dynein motor movement</p> Signup and view all the answers

    What are molecular motors involved in?

    <p>Intracellular transport</p> Signup and view all the answers

    During interphase, what are kinesins and dyneins involved in?

    <p>Transport and positioning of membrane enclosed organelles and vesicles</p> Signup and view all the answers

    What is responsible for the movement of cilia and flagella?

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

    What drives the polymerization and depolymerization of microtubules?

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

    What is the term for the process of changing chemical energy into mechanical energy and transporting cell structures along microtubules?

    <p>Motor movement</p> Signup and view all the answers

    What type of tubulin binds GTP reversibly and can be hydrolyzed to GDP?

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

    What is the role of basal bodies in cell structures?

    <p>Organizing microtubules for cilia and flagella formation</p> Signup and view all the answers

    What is the term for the process in which one end of a microtubule polymerises while the other end disassembles?

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

    What determines the rate of microtubule polymerisation?

    <p>The critical concentration of alpha-tubulin</p> Signup and view all the answers

    What are the hair-like cell appendages formed by microtubules and surrounded by a membrane called?

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

    Which molecular motors move toward the plus end of microtubules?

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

    What is the term for microtubule nucleation and organisation sites within the cell?

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

    What is involved in the formation of flagella and cilia?

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

    What type of movement do dyneins exhibit along microtubules?

    <p>Toward the minus end</p> Signup and view all the answers

    What is the term for the process of changing chemical energy into mechanical energy and transporting cell structures along microtubules?

    <p>Molecular motor activity</p> Signup and view all the answers

    Study Notes

    Microtubules and Molecular Motors: Key Concepts

    • Microtubules exhibit dynamic instability, with different rates of polymerisation and depolymerisation at their plus and minus ends.
    • Treadmilling occurs when one end of a microtubule polymerises while the other end disassembles.
    • The rate of microtubule polymerisation is dependent on the critical concentration of alpha-tubulin.
    • Microtubules form in vitro through three phases: lag phase, growth phase, and steady state phase.
    • Microtubule-organising centres (MTOCs) such as centrosomes and basal bodies play a central role in microtubule nucleation and organisation.
    • Centrosomes contain centrioles and pericentriolar material, serving as nucleation sites for microtubule assembly.
    • Basal bodies, formed from centrioles, are involved in the formation of flagella and cilia.
    • Cilia and flagella are hair-like cell appendages formed by microtubules and surrounded by a membrane, with cilia being more numerous and shorter.
    • Molecular motors, such as kinesins and dyneins, can change chemical energy into mechanical energy and transport cell structures along microtubules.
    • Kinesins move toward the plus end of microtubules, while dyneins move toward the minus end.
    • Molecular motors associated with microfilaments are myosins, which move toward the plus end.
    • The motor movement consists of four steps: filament binding, conformational change, filament release, and conformational relaxation.

    Microtubules and Molecular Motors: Key Concepts

    • Microtubules exhibit dynamic instability, with different rates of polymerisation and depolymerisation at their plus and minus ends.
    • Treadmilling occurs when one end of a microtubule polymerises while the other end disassembles.
    • The rate of microtubule polymerisation is dependent on the critical concentration of alpha-tubulin.
    • Microtubules form in vitro through three phases: lag phase, growth phase, and steady state phase.
    • Microtubule-organising centres (MTOCs) such as centrosomes and basal bodies play a central role in microtubule nucleation and organisation.
    • Centrosomes contain centrioles and pericentriolar material, serving as nucleation sites for microtubule assembly.
    • Basal bodies, formed from centrioles, are involved in the formation of flagella and cilia.
    • Cilia and flagella are hair-like cell appendages formed by microtubules and surrounded by a membrane, with cilia being more numerous and shorter.
    • Molecular motors, such as kinesins and dyneins, can change chemical energy into mechanical energy and transport cell structures along microtubules.
    • Kinesins move toward the plus end of microtubules, while dyneins move toward the minus end.
    • Molecular motors associated with microfilaments are myosins, which move toward the plus end.
    • The motor movement consists of four steps: filament binding, conformational change, filament release, and conformational relaxation.

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    Description

    Test your knowledge of microtubules and molecular motors with this quiz. Explore key concepts such as dynamic instability, treadmilling, microtubule polymerisation, MTOCs, and the functions of molecular motors like kinesins, dyneins, and myosins.

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