Question 1

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

Accepted Answer

They mediate anterograde transport of proteins from the endoplasmic reticulum to the Golgi apparatus.

Question 2

A temperature-sensitive mutant yeast strain accumulates vesicles in the cytoplasm at 37°C but not at room temperature. Which gene is most likely mutated?

Accepted Answer

sec1

Question 3

Which of the following steps occurs FIRST during the synthesis and processing of insulin in pancreatic β-cells?

Accepted Answer

Cleavage of the signal peptide as the nascent chain enters the ER lumen

Question 4

Which of the following is a critical function of calnexin and calreticulin in the endoplasmic reticulum?

Accepted Answer

They retain incompletely folded glycoproteins in the ER until proper folding is achieved.

Question 5

Which of the following statements about the vesicular monoamine transporter (VMAT) is CORRECT?

Accepted Answer

VMAT harnesses the proton gradient generated by vATPase to transport neurotransmitters into vesicles.

Question 6

Which of the following is NOT a criterion for designating a molecule as a neurotransmitter?

Accepted Answer

It must be a peptide or protein.

Question 7

In the context of the secretory pathway, what is the main function of the trans-Golgi network (TGN)?

Accepted Answer

Sorting and packaging of proteins for delivery to their final destinations

Question 8

Which of the following best explains why temperature-sensitive mutants are useful for studying the secretory pathway in yeast?

Accepted Answer

They allow for the identification of essential genes by observing loss of function at non-permissive temperatures.

Question 9

Which of the following processes is responsible for the initial targeting of secretory proteins to the endoplasmic reticulum?

Accepted Answer

Binding of the signal recognition particle (SRP) to the signal sequence on the nascent polypeptide

Question 10

Which of the following best describes the difference between peptide hormone and amine neurotransmitter packaging?

Accepted Answer

Peptide hormones are synthesized on ER-bound ribosomes and processed through the Golgi, while amine neurotransmitters are synthesized in the cytosol and packaged into vesicles at the synaptic terminal.

Question 11

A mutation in the sec61 gene would most likely disrupt which of the following processes?

Accepted Answer

Transport of nascent polypeptides into the ER lumen during translation

Question 12

Which of the following is TRUE regarding the role of vATPase in neurotransmitter packaging?

Accepted Answer

vATPase hydrolyzes ATP to pump H+ into vesicles, creating a proton gradient used by neurotransmitter transporters.

Question 13

Which of the following best explains why the proper folding of proteins in the ER is essential before they can exit to the Golgi apparatus?

Accepted Answer

Only properly folded proteins can be recognized by cargo receptors for packaging into transport vesicles.

Question 14

Which of the following is a direct consequence of a sec7 mutation in yeast cells?

Accepted Answer

Formation of a massively inflated trans-Golgi network (TGN)

Question 15

Which of the following is the correct sequence of events for the synthesis and release of a peptide hormone such as insulin?

Accepted Answer

Synthesis on ER-bound ribosomes → folding and disulfide bond formation in ER → transport to Golgi → cleavage and packaging in secretory vesicles → exocytosis

Question 16

Which of the following best describes the function of the signal peptidase enzyme during co-translational transport?

Accepted Answer

It cleaves the signal sequence from the nascent polypeptide as it enters the ER lumen.

Question 17

Which of the following is a key difference between the packaging of neurotransmitters and peptide hormones?

Accepted Answer

Peptide hormones are synthesized and packaged through the ER and Golgi, while neurotransmitters are synthesized in the cytosol and packaged into vesicles at the synaptic terminal.

Question 18

Which of the following best explains why VMAT inhibitors such as reserpine can be used as antipsychotic drugs?

Accepted Answer

They block the packaging of monoamine neurotransmitters into vesicles, reducing their release.

Question 19

Which of the following is the main driving force for neurotransmitter uptake into synaptic vesicles by VMAT?

Accepted Answer

Proton gradient (ΔpH) generated by vATPase

Synthesis, Packaging, and Release of Signaling Molecules: The Secretory Pathway in Eukaryotic Cells

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