Q: Which of the following equations correctly represents the ATP-dependent acidification of the lysosome?

$$ \mathrm{H}^+_{\text{cytosol}} \xrightarrow{\text{ATPase}} \mathrm{H}^+_{\text{lysosome}} $$

Question 1

Which of the following best describes the role of the Trans-Golgi Network (TGN) in vesicle trafficking within the cell?

Accepted Answer

It is the sorting compartment that directs vesicles toward the plasma membrane, lysosomes, or secretory vesicles based on specific signals.

Question 2

A newly synthesized lysosomal enzyme is targeted to the lysosome by which of the following signals added in the Golgi?

Accepted Answer

Mannose-6-phosphate (Man-6-P) modification

Question 3

Which coat protein is primarily responsible for the formation of vesicles that transport lysosomal enzymes from the TGN to late endosomes?

Accepted Answer

Clathrin

Question 4

A patient presents with a lysosomal storage disease in which none of the lysosomal enzymes are correctly sorted to lysosomes. Which mutation is most likely responsible for this phenotype?

Accepted Answer

Mutation in the Man-6-P phosphotransferase enzyme

Question 5

During receptor-mediated endocytosis, what is the fate of the LDL receptor after internalization?

Accepted Answer

It is recycled back to the plasma membrane via the early endosome.

Question 6

Which of the following equations correctly represents the ATP-dependent acidification of the lysosome?

Accepted Answer

$$ \mathrm{H}^+_{	ext{cytosol}} \xrightarrow{	ext{ATPase}} \mathrm{H}^+_{	ext{lysosome}} $$

Question 7

Which process is responsible for the uptake of large solid particles, such as bacteria, by immune cells?

Accepted Answer

Phagocytosis

Question 8

What is the main difference between pinocytosis and phagocytosis?

Accepted Answer

Pinocytosis involves uptake of fluids and small molecules, while phagocytosis engulfs large particles.

Question 9

Which of the following best explains why the pH of endocytosed vesicles and endosomes decreases over time?

Accepted Answer

Active transport of H$$^+$$ ions into the vesicle via ATP-dependent pumps

Question 10

Which sorting signal is required for a protein to be retained in the endoplasmic reticulum (ER)?

Accepted Answer

ER retention signal

Question 11

A mutation in the clathrin adaptor protein AP2 would most directly affect which cellular process?

Accepted Answer

Receptor-mediated endocytosis at the plasma membrane

Question 12

Which of the following is a real-world consequence of defective LDL receptor-mediated endocytosis?

Accepted Answer

High blood cholesterol and low cellular cholesterol (hypercholesterolemia)

Question 13

Which of the following best describes the function of SNARE proteins in vesicle trafficking?

Accepted Answer

They mediate the fusion of vesicle membranes with target membranes.

Question 14

Which of the following equations represents the recognition site for N-linked glycosylation in the ER?

Accepted Answer

$$ 	ext{Asn-X-Ser/Thr} $$

Question 15

Which of the following is TRUE regarding the balance of membrane flow in the cell?

Accepted Answer

Secretion and endocytosis must be balanced to maintain proper plasma membrane size.

Question 16

Which of the following is a function of acid hydrolases found in lysosomes?

Accepted Answer

Degradation of macromolecules in an acidic environment

Question 17

Which of the following is a multi-step process that involves both endocytosis and lysosomal degradation?

Accepted Answer

Receptor-mediated endocytosis of LDL followed by lysosomal processing of cholesterol

Question 18

Which of the following best explains why some proteins are sorted to regulated secretory vesicles rather than constitutive secretory vesicles?

Accepted Answer

They aggregate in the TGN in response to specific signals, awaiting a stimulus for release.

Question 19

Which of the following is a correct sequence of events for the targeting of lysosomal hydrolases?

Accepted Answer

Synthesis in the cytosol → addition of Man-6-P in the Golgi → recognition by Man-6-P receptor → sorting into clathrin-coated vesicles → delivery to late endosome/lysosome

Vesicle Trafficking: Pathways from the Golgi to the Cell Surface and Lysosomes

Guida di studio - Domande di pratica

Study guide - Flashcard