Practice Exam 2 Questions

Question 1

Sar1 initiates the assembly of:

Answer 1

COPII coat on the ER

Question 2

GTP hydrolysis causes a Rab protein to:

Answer 2

dissociate from the membrane

Question 3

To enter the calnexin cycle in the ER, a protein needs to:

Answer 3

Contain an N-linked oligosaccharide

Question 4

List the three major types of coated vesicles in the cell and describe their donor and recipient membrane compartments.

Answer 4

1. COPI: Golgi to ER and within Golgi stacks (retrograde)
2. COP II: ER to Golgi
3. Clathrin: trans-Golgi to Endosome; PM to endosome

Question 5

Blocking NSF activity leads to what?

Answer 5

Vesicle transport is arrested

Question 6

What type of energy does dynamic use to drive the release of clathrin-coated vesicles form the donor membrane?

Answer 6

GTP

Question 7

Where does ER-associated degradation occur?

Answer 7

Cytosol

Question 8

Describe the process of LDL mediation.

Answer 8

1. Receptor binds LDL due to binding affinity at extracellular pH.
2. This recruits components of the clathrin coat for coat formation.
3. After vesicle loses coat it binds and fuses with endosome; receptor releases LDL due to lowered pH and lack of binding affinity.
4. Receptor is recycled via vesicle to the PM
5. LDL goes on to be degraded in the lysosome.

Question 9

Which type of energy is required for the formation of COPII coats?

Answer 9

GTP

Question 10

What feature distinguishes regulated exocytosis from constitutive exocytosis?

Answer 10

The requirement of trigger signal for vesicle fusion.

Question 11

Which compartment is NOT topologically equivalent to the extracellular space?

Answer 11

The interior of the nucleus