Cytoskeleton: Microtubules Composition and Dynamics
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Questions and Answers

What is the size of microtubules (MT) in diameter?

  • 36 nm
  • 48 nm
  • 12 nm
  • 24 nm (correct)

Which end of a microtubule (MT) exhibits faster assembly and disassembly?

  • The (-) end
  • The middle section
  • Both ends show the same speed
  • The (+) end (correct)

What is the composition of tubulin subunits in microtubules?

  • Polymers of single tubulin type
  • Heterotrimers of α, β, and γ tubulin monomers
  • Heterodimers of α and β tubulin monomers (correct)
  • Homodimers of α tubulin monomers

Which agent binds to tubulin and stabilizes microtubules (MTs)?

<p>Taxol (A)</p> Signup and view all the answers

What is the main role of MAP1, MAP2, and Tau in relation to microtubules?

<p>Crosslink microtubules to intermediate filaments (C)</p> Signup and view all the answers

Which structure is primarily composed of stable, long-lived microtubules?

<p>Cilia and flagella (B)</p> Signup and view all the answers

What is the function of actin filaments in cellular motility?

<p>Supporting stress fibers (A)</p> Signup and view all the answers

How does treadmilling occur in actin filaments?

<p>Subunits are released at the (-) end and reassemble at the (+) end (B)</p> Signup and view all the answers

What is the function of thymosin β4 in relation to actin assembly?

<p>Inhibition of actin assembly (C)</p> Signup and view all the answers

Which protein is involved in the regulation of actin polymerization, length, and stability?

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

Which agent leads to depolymerization of actin filaments?

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

What is the size range of actin filaments in diameter?

<p>7-9 nm (D)</p> Signup and view all the answers

Which protein is responsible for (-) end-directed movement along microtubules?

<p>Dynein (C)</p> Signup and view all the answers

What is the primary function of microtubules in intracellular transport?

<p>Function as tracks for vesicles, proteins, and organelles (D)</p> Signup and view all the answers

Which disease is characterized by the hyperphosphorylation of tau protein?

<p>Alzheimer's disease (B)</p> Signup and view all the answers

What is the role of dynein arms in cilia and flagella bending?

<p>Produce a bending force by sliding between microtubule pairs (D)</p> Signup and view all the answers

What structure is responsible for the movement of cilia and flagella?

<p>Radial spokes and central pair MTs (D)</p> Signup and view all the answers

Which protein complex links dynein to vesicles and microtubules?

<p><strong>Dynactin complex</strong> (B)</p> Signup and view all the answers

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