Question 1

Which cytoskeletal element is primarily responsible for maintaining mechanical strength in epithelial cells, and what is the main protein involved?

Accepted Answer

Intermediate filaments; keratin

Question 2

A scientist treats dividing cells with paclitaxel (Taxol). What is the most likely effect on microtubule dynamics, and why is this drug used in cancer therapy?

Accepted Answer

Microtubules are stabilized, preventing disassembly and inhibiting mitosis

Question 3

Which cytoskeletal element is most likely to be involved in the rapid movement of vesicles within a neuron, and what energy molecule is required for its assembly?

Accepted Answer

Microtubules; GTP

Question 4

A mutation in the gene encoding tau protein is linked to neurodegenerative diseases. What is the primary function of tau in neurons?

Accepted Answer

Stabilizes microtubule bundles in axons

Question 5

Which cytoskeletal element is most likely to be disrupted by colchicine, and what is the molecular mechanism of action?

Accepted Answer

Microtubules; binds β-tubulin and inhibits assembly

Question 6

During treadmilling of actin filaments, which equation best describes the condition for steady-state filament length?

Accepted Answer

$$C_{+} \u003e C \u003e C_{-}$$

Question 7

Which cytoskeletal element is NOT involved in cell motility, and why?

Accepted Answer

Intermediate filaments; they lack polarity and motor proteins

Question 8

A cell is observed to have a contractile ring during cytokinesis. Which cytoskeletal element and associated protein are primarily responsible for this process?

Accepted Answer

Microfilaments; myosin

Question 9

Which cytoskeletal element is most likely to be found in the nuclear lamina, and what is its primary function?

Accepted Answer

Intermediate filaments; structural support of the nuclear envelope

Question 10

A researcher uses fluorescence microscopy to visualize cytoskeletal elements. Which element would appear as hollow tubes with a diameter of approximately 25 nm?

Accepted Answer

Microtubules

Question 11

Which protein complex is responsible for nucleating microtubules at the centrosome, and what is its effect on microtubule polarity?

Accepted Answer

γ-TuRC; anchors minus ends and allows plus ends to grow outward

Question 12

Which cytoskeletal element is most likely to be involved in the formation of lamellipodia during cell migration, and which protein promotes its assembly?

Accepted Answer

Microfilaments; profilin

Question 13

A cell is exposed to nocodazole. What is the expected outcome for microtubule dynamics, and how does this differ from the effect of paclitaxel?

Accepted Answer

Microtubules are depolymerized, while paclitaxel stabilizes them

Question 14

Which cytoskeletal element is most likely to be found in prokaryotes, and what is its functional analog in eukaryotes?

Accepted Answer

Microtubules; FtsZ (tubulin-like)

Question 15

Which equation best describes the relationship between tubulin concentration and microtubule assembly at the plus end?

Accepted Answer

$$C \u003e C_{c,+}$$

Question 16

A patient with a keratin mutation presents with skin blistering. Which cytoskeletal element is affected, and what is the consequence for cell structure?

Accepted Answer

Intermediate filaments; reduced mechanical strength

Question 17

Which cytoskeletal element is most likely to be involved in the movement of cilia and flagella, and what structural feature distinguishes it?

Accepted Answer

Microtubules; doublet arrangement stabilized by MIPs

Question 18

Which cytoskeletal element is most likely to be involved in cytoplasmic streaming in plant cells, and which motor protein is required?

Accepted Answer

Microfilaments; myosin

Question 19

Which cytoskeletal element is most likely to be stabilized by acetylation, and what is the effect on its dynamics?

Accepted Answer

Microtubules; increased stability and reduced dynamic instability

Question 20

A cell is observed to have mixed polarity of microtubules in its dendrites. Which protein is most likely to be involved in creating looser microtubule bundles in this region?

Accepted Answer

MAP2

Cytoskeletal Systems: Structure, Function, and Dynamics

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