Question 1

Which of the following best describes the structural differences between actin filaments, intermediate filaments, and microtubules?

Accepted Answer

Actin filaments are polymers of globular actin, intermediate filaments are polymers of fibrous proteins, and microtubules are polymers of tubulin dimers.

Question 2

A patient presents with chronic respiratory infections, infertility, and abnormal left-right organ patterning. Which cytoskeletal structure is most likely dysfunctional?

Accepted Answer

Microtubules

Question 3

Which of the following statements about actin filament treadmilling is correct?

Accepted Answer

ATP-bound actin monomers add preferentially to the plus end, while ADP-bound monomers dissociate from the minus end.

Question 4

Which protein is responsible for anchoring the spectrin-actin network to the plasma membrane in red blood cells?

Accepted Answer

Ankyrin

Question 5

A mutation in which gene is most likely to cause hereditary spherocytosis with round red blood cells due to membrane instability?

Accepted Answer

ANK1

Question 6

Which of the following best explains why microtubules are essential for mitosis?

Accepted Answer

They assemble into the mitotic spindle, which segregates chromosomes.

Question 7

Which cytoskeletal element is most directly involved in resisting mechanical stress in epithelial tissues?

Accepted Answer

Intermediate filaments (keratins)

Question 8

A drug that stabilizes microtubules and prevents their depolymerization would most likely interfere with which cellular process?

Accepted Answer

Chromosome segregation during mitosis

Question 9

Which of the following is a function of the nuclear lamins?

Accepted Answer

Providing structural support to the nuclear envelope and organizing chromatin

Question 10

A patient with a mutation in the GFAP gene presents with seizures, neuropathy, and Rosenthal fibers in the brain. Which cytoskeletal element is affected?

Accepted Answer

Intermediate filaments (astrocyte-specific)

Question 11

Which of the following best describes the role of myosin II in non-muscle cells?

Accepted Answer

It interacts with actin to form the contractile ring during cytokinesis.

Question 12

Which of the following proteins is a microtubule motor responsible for retrograde transport?

Accepted Answer

Dynein

Question 13

A patient with a mutation in the LMNA gene exhibits premature aging, hair loss, and cardiovascular disease. What is the underlying cellular defect?

Accepted Answer

Defective nuclear lamina due to misfolded lamin A (progerin) accumulation

Question 14

Which of the following best explains the effect of colchicine on dividing cells?

Accepted Answer

It prevents microtubule assembly, inhibiting mitotic spindle formation.

Question 15

Which of the following is a key difference between actin filaments and microtubules?

Accepted Answer

Actin filaments use ATP for polymerization, while microtubules use GTP.

Question 16

Which cytoskeletal element is most directly involved in the formation of microvilli in intestinal epithelial cells?

Accepted Answer

Actin filaments

Question 17

A scientist treats cells with a drug that inhibits ATP hydrolysis in actin filaments. What is the most likely effect on actin dynamics?

Accepted Answer

Actin filaments will become more stable due to persistent ATP-bound actin.

Question 18

Which of the following best describes the function of the Arp2/3 complex?

Accepted Answer

It nucleates new actin filaments, promoting branched actin networks.

Question 19

Which cytoskeletal element is most important for axonal transport in neurons?

Accepted Answer

Microtubules

Question 20

A patient with blistering skin and nail deformities is found to have a mutation in a keratin gene. Which cytoskeletal structure is affected?

Accepted Answer

Intermediate filaments

The Cytoskeleton: Structure, Function, and Clinical Correlations

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