Cytoskeletal Microtubules & Microfilaments Quiz
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Questions and Answers

What is the primary role of microtubule-associated proteins (MAPs) in cellular functions?

  • To assist in the polymerization of actin filaments.
  • To degrade microtubules into tubulin.
  • To prevent depolymerization of microtubules and aid in intracellular transport. (correct)
  • To initiate the synthesis of new microtubules from existing ones.

During which cellular process do centrioles contribute to the formation of the spindle apparatus?

  • Transcription
  • Protein synthesis
  • Cell division (correct)
  • Cytokinesis

What mechanism allows kinesin to transport vesicles within the cell?

  • Binding to actin filaments.
  • Releasing chemical signals to attract the vesicle.
  • Creating negative pressure within the vesicle.
  • Utilizing energy derived from the hydrolysis of ATP. (correct)

How does colchicine exert its anti-inflammatory effects in acute gouty arthritis?

<p>By preventing microtubule polymerization in leukocytes. (A)</p> Signup and view all the answers

The structure of centrioles is described as being composed of how many microtubule triplets?

<p>Nine (D)</p> Signup and view all the answers

Which statement best describes the dynamic nature of microtubules?

<p>Microtubules frequently change length, primarily growing and shortening at their plus ends. (D)</p> Signup and view all the answers

What is the role of microtubules during cell division?

<p>They facilitate rapid polymerization to form the mitotic spindle. (B)</p> Signup and view all the answers

How is the structure of microtubules related to their function?

<p>They are made up of 13 parallel protofilaments which enable them to serve as intracellular pathways. (B)</p> Signup and view all the answers

What role do motor proteins play in relation to microtubules?

<p>Motor proteins facilitate the intracellular movement of organelles and vesicles along microtubules. (C)</p> Signup and view all the answers

Which of the following statements about microfilaments is most accurate?

<p>Microfilaments are constructed from actin and are crucial for cellular motility. (A)</p> Signup and view all the answers

Flashcards

Microtubule disruption by drugs

Certain drugs interfere with microtubule assembly, altering cell functions in various ways

Colchicine's anti-inflammatory effect

Colchicine prevents leukocyte movement and inflammation, aiming to stop gout

Microtubule-associated proteins (MAPs)

Proteins that help cell components move along microtubules

Centrioles' role in cell division

Centrioles organize microtubules to form the spindle apparatus needed for cell division

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Dynein and Kinesin

Motor proteins that move vesicles in opposite directions along microtubules

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What are microtubules?

Microtubules are long, hollow tubes made of protein subunits that act as intracellular tracks for transport within cells.

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What is the centrosome?

The centrosome is a region near the nucleus that acts as the organizing center for microtubules, containing structures called centrioles.

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Tubulin subunits

Microtubules are made of repeating protein units called α- and β-tubulin, which form dimers that assemble into protofilaments.

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Why are microtubules dynamic?

Microtubules are dynamic structures that constantly grow and shrink, with the plus end being the site of growth and shortening.

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What is the role of microtubules in cell division?

During cell division, microtubules rapidly polymerize to form the mitotic spindle, which helps to separate chromosomes.

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Study Notes

Cytoskeletal Microtubules & Microfilaments & Motility

  • Students will be able to correlate the molecular organization of microtubules to their dynamic nature
  • Interpret structural adaptations of microtubules to their function
  • Correlate relevant motor proteins in cell trafficking to microtubules
  • Appraise the importance of microtubules as a drug target
  • Correlate the molecular structure of actin to its function

Cytoskeleton

  • The cytoplasm of animal cells contains a cytoskeleton, a complex 3D network supporting cell shape
  • It's actively involved in cellular motion, including organelles, vesicles, and even the whole cell
  • The cytoskeleton includes: thin filaments (microfilaments), intermediate filaments, and microtubules.

Microtubules

  • Microtubules (MTs) are long, hollow structures acting as intracellular pathways
  • The centrosome, near the nucleus, has y-tubulin complexes that nucleate microtubules in a ring-shape fashion
  • Microtubules are dynamic; constantly changing length via growth and shortening, primarily at their plus end (away from the nucleus)
  • Average microtubule half-life is about 10 minutes
  • Composed of 13 parallel protofilaments consisting of a- and b-tubulin heterodimers

Functions of MTs

  • Maintain cell shape and rigidity
  • Regulate movement of organelles and vesicles
  • Enable intracellular transport; dynein moves vesicles towards the minus end, kinesin toward the plus end
  • Create a structure for cilia and flagellum
  • Involved in cell division; formation of the mitotic spindle

Clinical Correlation

  • Drugs like colchicine can disrupt microtubule formation, affecting leukocyte migration and inflammatory responses, useful in treating conditions like gout

Microtubule-Associated Proteins (MAPs)

  • Motor proteins assist in moving organelles and vesicles inside the cell
  • Two major families are dynein and kinesin, moving along microtubules in opposite directions depending on ATP presence

Centrioles

  • Cylindrical structures composed of nine microtubule triplets
  • Part of the centrosome, a microtubule organizing center
  • Essential for cell division by forming the spindle apparatus
  • Associated with formation of cilia and flagella

Actin Filaments (Microfilaments)

  • Composed of two coiled actin chains (F-actin) made from globular actin (G-actin) monomers
  • Possess a plus end (faster-growing) and a minus end (slower-growing)
  • Form different structures:
    • Contractile bundles: Parallel, loosely-arranged filaments involved in cytokinesis, organelle movement, and endocytosis
    • Gel-like networks: Provide structural integrity (cell cortex)
    • Bundles: Found in microvilli
    • Focal points: Points of contact with the extracellular matrix

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L13 Cytoskeleton Elements & Cell Division PDF

Description

This quiz explores the organization and function of microtubules and microfilaments within the cytoskeleton. Students will learn about their structural adaptations and roles in cellular motility, as well as their potential as drug targets. Enhance your understanding of these vital components in cellular architecture and dynamics.

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