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BIOC 384 Exam 3

Terms in this set (14)

For the following reaction A→ B, if at equilibrium delta Gº'> 0, what can be said about the directionality of the reaction?

A. strongly favored in both directions
B. strongly favored in the forward direction
C. strongly favored in the reverse direction
D. not enough information is given
C. strongly favored in the reverse direction
Which protein in the insulin receptor signaling pathway is capable of autophosphorylation?

A. phosphatidylinositide 3-kinase (PI-3K)
B. insulin receptor substrate (IRS)
C. phosphate and tensin homolog (PTEN)
D. insulin receptor (IR)
D. insulin receptor (IR)
Caspase 3 is responsible for_______________.

A. activating caspase 8
B. dephosphorylating FasL
C. phosphorylating Fas
D. degrading key regulatory molecules.
D. degrading key regulatory molecules.
In the following series of reactions, what is the shared intermediate?

A. glucose-6-P
B. ATP
C. fructose-6-P
D. fructose-1,6-P
E. ADP
C. fructose-6-P
If there were a technique that allowed one to isolate EGFR1 and EGFR2 at discrete steps along the activation pathway, which of the following would be isolated?

A. A monomer of EGFR1 that contains phosphotyrosines
B. A monomer of EGFR2 that contains phosphotyrosines
C.A dimer in which EGFR1 contains phosphotyrosines but EGFR2 does not.
D. A dimer in which EGFR2 contains phosphotyrosines but EGFR1 does not.
D. A dimer in which EGFR2 contains phosphotyrosines but EGFR1 does not.
Caspases (cysteine-aspartate proteases) function as "cutioners" in the cell death pathway. Choose three reasons why it makes sense that they function in this role rather than some other biomolecule.

A. Caspases are rapidly produced by the ribosome after the signal for cell death is received.

B. Caspases must be activated by proteolytic cleavagge to convert the inactive zymogen to the active form-this provides a means to control caspase activity by initiating the cleavage reaciton.

C. Caspases are enzymes that function catalytically and therefore can do a lot of damage in a very short amount of time

D. Caspases have preferred substrate recognition sites for cleavage, and therefore can preferentially degrade other proteins

E. Caspases have longer stability in the cell than most proteins, since they are readily refolded by chaperones
B. Caspases must be activated by proteolytic cleavagge to convert the inactive zymogen to the active form-this provides a means to control caspase activity by initiating the cleavage reaciton.

C. Caspases are enzymes that function catalytically and therefore can do a lot of damage in a very short amount of time

D. Caspases have preferred substrate recognition sites for cleavage, and therefore can preferentially degrade other proteins
If the standard free energy change for the reaction converting A to B is unfavorable, how can this reaction proceed in the forward direction under cellular conditions? Select TWO correct answers.

A. The reaction cannot proceed in the forward direction under any circumstances since the standard free energy change is positive

B. Decrease the cellular concentration of B until the actual free energy change is now negative.

C. Decrease the cellular concentrations of A until the actual free energy change is now negative

D. Couple the reaction to an exergonic reaction such as ATP hydrolysis.
B. Decrease the cellular concentration of B until the actual free energy change is now negative.

D. Couple the reaction to an exergonic reaction such as ATP hydrolysis.
Below is shown a short sequence of a protein. Which of the following protein subdomains would most likely bind to this sequence?

A. SHP
B. SH2a
C. SH2
D. SH3
D. SH3
What is the function of growth factor receptor-bound 2 (GRB2) protein in RTK signaling?

A. It is an adaptor protein that binds to phosphotyrosine residues in RTKs and also binds to GEF proteins
B. It is a tyrosine kinase protein that phosphorylates arginine residues in PI-3K and in phospholipase C
C. It is an adaptor protein that binds to G proteins like Ras and Gsa and also MAPK, Raf, and ERK
D. It is an adaptor protein that binds to phosphoserine residues in IRSs and to GEF proteins like PI-3K
A. It is an adaptor protein that binds to phosphotyrosine residues in RTKs and also binds to GEF proteins
Predict which bond of a target protein would be cleaved by caspase 3 executioner enzyme.

A. 1
B. 4
C. 2
D. 3
B. 4
Which of the following is true of procaspase 8?

A. It is a kinase
B. It can be activated by phosphorylation
C. It is proteolytically inactive
D. It can cleave caspase 3
C. It is proteolytically inactive
The TNF signaling pathway stimulates both an apoptosis and a cell survival pathway in the same well. What molecular mechanism determines whether the cell survives or dies?

A. Cell death or survival in a TNF receptor stimulated cell is determined by the relative expression level of downstream signaling proteins in the propoptotic and anti-apoptotic pathways
B. Cell death or survival in a TNF receptor stimulated cell is determined by the relative amounts of TRADD protein produced by TNF signaling
C. Cell death or survival in a TNF receptor stimulated cell is determined by the number of times the TNF receptor is stimulated. The default state is cell survival, however, if the TNF receptor is stimulated multiple times, then the overall signal for cell death will predominate
D. Cell death or survival in a TNF receptor stimulated cell is determined by the signals received from neighboring cells. If the neighbor cell is secreting "survival" stimulants, then the TNF receptor stimulated cell will also survive
A. Cell death or survival in a TNF receptor stimulated cell is determined by the relative expression level of downstream signaling proteins in the propoptotic and anti-apoptotic pathways
Place the following steps in proper order

A. phosphorylation of RTK cytoplasmic tails
B. activation of downstream signaling pathways
C. ligand binding, receptor dimerization, and kinase activation
D. protein binding to RTK phosphotyrosines and phosphorylation of target proteins
C, A, D, B
If GRB2 were truncated so that the N-terminal domain was missing, the truncated protein would be unable to bind the _____
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