Question 1

A patient presents with skin blistering after minor trauma. Genetic analysis reveals a mutation in the K14 gene. Which cytoskeletal component is most directly affected, and what is the primary function of this component?

Accepted Answer

Intermediate filaments; provide mechanical tensile strength

Question 2

Which of the following best explains why intermediate filaments cannot serve as tracks for motor proteins?

Accepted Answer

They are nonpolar due to antiparallel tetramer assembly

Question 3

A researcher treats dividing cells with Taxol (Paclitaxel). What is the most likely cellular effect, and what is the molecular mechanism?

Accepted Answer

Stabilization of microtubules, freezing the mitotic spindle and blocking mitosis

Question 4

During axonemal movement in cilia, which of the following is true regarding the energy requirements and structural components?

Accepted Answer

ATP is required for dynein motor activity; GTP is required for axoneme assembly

Question 5

Which of the following best describes the process of treadmilling in actin filaments?

Accepted Answer

Subunits add at the (+) end and dissociate at the (–) end, with no net change in filament length

Question 6

A cell is exposed to a Rho GTPase agonist. Which cytoskeletal structure is most likely to be enhanced, and what is its function?

Accepted Answer

Stress fibers; contractile bundles important for cell shape and cytokinesis

Question 7

A patient with scurvy exhibits fragile blood vessels and poor wound healing. Which biochemical defect underlies this condition?

Accepted Answer

Impaired hydroxylation of proline and lysine residues in collagen

Question 8

Which of the following best explains why gap junctions do not contribute to tissue mechanical strength?

Accepted Answer

They are formed by connexins and lack cytoskeletal attachments

Question 9

A scientist removes radial spokes and nexin links from the axoneme of a cilium. What is the most likely outcome when ATP is added?

Accepted Answer

Ciliary doublets slide past each other without bending

Question 10

Which of the following best describes the role of the MTOC (centrosome) in microtubule organization?

Accepted Answer

It anchors and caps the minus (–) end, leaving the plus (+) end dynamic

Question 11

A muscle cell is exposed to sarin, an acetylcholinesterase inhibitor. What is the most immediate effect on muscle physiology?

Accepted Answer

Continuous depolarization of the sarcolemma and persistent muscle contraction

Question 12

Which of the following is a correct sequence for intermediate filament assembly?

Accepted Answer

Monomer $$\rightarrow$$ Dimer $$\rightarrow$$ Tetramer $$\rightarrow$$ Protofilament $$\rightarrow$$ Filament

Question 13

A cell is treated with an MLCK inhibitor. Which process is most directly affected?

Accepted Answer

Smooth muscle contraction via myosin phosphorylation

Question 14

Which of the following best describes the function of fibronectin in the extracellular matrix?

Accepted Answer

It is a multiadhesive glycoprotein that binds integrins and fibrin

Question 15

A carcinoma cell is metastasizing and must breach the basal lamina. Which enzyme is most critical for this process, and what is its substrate?

Accepted Answer

Matrix metalloproteinase (Type IV collagenase); Type IV collagen

Question 16

Which of the following statements about the sarcomere during muscle contraction is correct?

Accepted Answer

The I band and H zone narrow, but the A band length does not change

Question 17

Which of the following best explains why actin is highly conserved across eukaryotes?

Accepted Answer

Its structure is essential for fundamental processes like cell division and motility

Question 18

A cell is observed to have abundant lamellipodia at its leading edge. Which Rho GTPase is most likely activated, and what is the cytoskeletal basis for this structure?

Accepted Answer

Rac; branched actin meshwork

Question 19

Which of the following is a unique feature of plant cell walls compared to animal extracellular matrix?

Accepted Answer

Presence of pectins rich in galacturonic acid

Question 20

A mutation in the gene encoding $$eta-$$tubulin impairs GTP binding. Which cellular process is most likely to be directly affected?

Accepted Answer

Microtubule polymerization and mitotic spindle formation

Cytoskeleton, Cellular Motility, and Extracellular Matrix: Study Notes (Chapters 13–15)

Study Guide - Practice Questions

Study Guide - Flashcards