Question 1

Which of the following best describes the primary function of COPII-coated vesicles in the secretory pathway?

Accepted Answer

Transport of newly synthesized proteins from the rough ER to the cis-Golgi

Question 2

A mutation in the Sar1 GTPase that prevents GTP hydrolysis would most likely result in which of the following cellular phenotypes?

Accepted Answer

Accumulation of coated vesicles unable to uncoat after budding

Question 3

Which sorting signal is recognized by the COPI coat for the retrieval of ER-resident membrane proteins?

Accepted Answer

Lys-Lys-X-X (KKXX)

Question 4

Which of the following steps is directly mediated by the hydrolysis of GTP by dynamin during clathrin-mediated endocytosis?

Accepted Answer

Pinching off (scission) of the clathrin-coated vesicle from the plasma membrane

Question 5

A patient has a genetic defect in the Mannose 6-phosphate (M6P) receptor. Which cellular process would be most directly affected?

Accepted Answer

Delivery of lysosomal enzymes from the trans-Golgi network to lysosomes

Question 6

Which of the following best describes the role of SNARE proteins in vesicular trafficking?

Accepted Answer

They form coiled-coil complexes that mediate vesicle docking and fusion with target membranes

Question 7

Which of the following modifications occurs primarily in the cis-Golgi compartment during N-linked glycosylation?

Accepted Answer

Removal of three mannose residues

Question 8

A protein with a di-acidic (Asp-X-Glu) sorting signal in its cytosolic domain is most likely to be incorporated into which type of vesicle?

Accepted Answer

COPII-coated vesicle

Question 9

Which of the following is a key difference between the vesicular transport model and the cisternal maturation model of Golgi trafficking?

Accepted Answer

The cisternal maturation model proposes that Golgi cisternae mature as they move from cis to trans, carrying cargo with them

Question 10

Which of the following best explains why O-linked glycosylation is critical for the function of mucins?

Accepted Answer

It allows mucins to form the gel-like structure of mucus by adding carbohydrate side chains

Question 11

Which of the following is the correct sequence of events for the formation and fusion of a COPII-coated vesicle?

Accepted Answer

Sar1-GDP binds Sec12, exchanges GDP for GTP, recruits Sec23/Sec24, coat assembly, GTP hydrolysis, coat disassembly, vesicle fusion

Question 12

A researcher observes that a certain protein is retained in the ER and not transported to the Golgi. Which signal sequence is most likely present on this protein?

Accepted Answer

Lys-Asp-Glu-Leu (KDEL)

Question 13

Which of the following best describes the function of Rab GTPases in vesicular trafficking?

Accepted Answer

They control the docking of vesicles on target membranes by interacting with effector proteins

Question 14

Which of the following is a direct consequence of a defect in the AP2 complex in a human cell?

Accepted Answer

Impaired endocytosis of plasma membrane proteins

Question 15

Which of the following modifications is unique to the trans-Golgi compartment during N-linked glycosylation?

Accepted Answer

Addition of three galactose residues

Question 16

A scientist is studying a protein that is secreted only in response to a specific signal. Which pathway is this protein most likely to follow?

Accepted Answer

Regulated secretory pathway

Question 17

Which of the following best explains the role of the KDEL receptor in protein sorting?

Accepted Answer

It recognizes and retrieves ER-resident soluble proteins from the Golgi back to the ER

Question 18

Which of the following is a function of the Golgi apparatus?

Accepted Answer

Modification of N-linked oligosaccharides and O-linked glycosylation

Question 19

A protein is found to have the following sequence: Tyr-X-X-Φ (YXXΦ). Which vesicle coat and adaptor complex is most likely to recognize this signal for sorting?

Accepted Answer

Clathrin and AP1 or AP2

Vesicular Traffic, Secretion, and Endocytosis: Structure and Function in Cell Biology

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