Question 1

Which of the following best describes the function of the signal recognition particle (SRP) during cotranslational import of proteins into the endoplasmic reticulum (ER)?

Accepted Answer

SRP binds to the signal sequence of a nascent polypeptide and directs the ribosome to the ER membrane, where it interacts with the translocon.

Question 2

A mutation causes the loss of function of the v-SNARE protein in vesicle trafficking. Which cellular process would be most directly affected?

Accepted Answer

Fusion of transport vesicles with their target membranes, such as the Golgi or plasma membrane.

Question 3

During receptor-mediated endocytosis, which protein is primarily responsible for the formation of the vesicle coat?

Accepted Answer

Clathrin

Question 4

Which of the following best explains the difference between anterograde and retrograde transport in the endomembrane system?

Accepted Answer

Anterograde transport moves materials from the ER to the Golgi and then to the plasma membrane, while retrograde transport moves materials from the Golgi back to the ER.

Question 5

A patient is diagnosed with a genetic disorder affecting the function of lysosomal enzymes. Which cellular process is most likely impaired?

Accepted Answer

Degradation of macromolecules within the lysosome, leading to accumulation of undigested substrates.

Question 6

Which equation best represents the change in membrane potential during the depolarizing phase of an action potential in neurons?

Accepted Answer

$$\Delta V = V_{peak} - V_{rest}$$

Question 7

Which of the following statements about G protein-coupled receptor (GPCR) signaling is correct?

Accepted Answer

GPCRs activate heterotrimeric G proteins, which are 'on' when bound to GTP and 'off' when bound to GDP.

Question 8

In the RTK pathway, which event occurs immediately after ligand binding to the receptor?

Accepted Answer

Receptor dimerization or clustering

Question 9

Which of the following best describes the role of second messengers in signal transduction?

Accepted Answer

They amplify the signal received by a receptor, allowing for a larger cellular response.

Question 10

A scientist treats cells with taxol, a drug that stabilizes microtubules. Which cellular process is most likely to be affected?

Accepted Answer

Dynamic instability of microtubules, reducing their ability to undergo catastrophe and rescue.

Question 11

Which equation describes the treadmilling phenomenon in actin filaments, where the rate of addition at the plus end equals the rate of loss at the minus end?

Accepted Answer

$$r_{+} = r_{-}$$

Question 12

Which protein is responsible for branching of actin filaments in lamellipodia, facilitating cell movement?

Accepted Answer

Arp2/3 complex

Question 13

A muscle cell is exposed to a drug that blocks calcium release from the sarcoplasmic reticulum. What is the most immediate effect on muscle contraction?

Accepted Answer

Inhibition of troponin activation, preventing actin-myosin interaction and muscle contraction.

Question 14

Which equation best represents the energy requirement for microtubule assembly, where GTP is hydrolyzed by tubulin?

Accepted Answer

$$	ext{Tubulin-GTP} ightarrow 	ext{Tubulin-GDP} + 	ext{P}_i$$

Question 15

Which cell-cell junction is primarily responsible for preventing paracellular movement of solutes between epithelial cells?

Accepted Answer

Tight junctions

Question 16

Which extracellular matrix protein provides tensile strength to tissues such as tendons and skin?

Accepted Answer

Collagen

Question 17

A mutation in the gene encoding laminin affects the basal lamina. Which function is most likely disrupted?

Accepted Answer

Cell adhesion and structural support for epithelial tissues.

Question 18

Which equation best represents the amplification of a signal in a GPCR pathway, where one activated receptor leads to multiple second messenger molecules?

Accepted Answer

$$1 \ 	ext{GPCR} ightarrow n \ 	ext{cAMP}$$

Question 19

Which motor protein moves cargo toward the plus end of microtubules, and what is its energy source?

Accepted Answer

Kinesin; ATP hydrolysis

Cell Biology Study Guide: Endomembrane System, Signaling, Cytoskeleton, Cell Movement, Junctions, and Extracellular Matrix

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