Biochemistry Notes

BCH 3023 – Fall 2008 Final Exam, 12/8/2008 Name: _________________________________
1. The GTP analog, ,-imidoguanosine 5’-triphosphate (Gpp(NH)p), shown below, cannot be hydrolyzed between the  and  phosphates. Predict the effect of microinjection of Gpp(NH)p of G-protein coupled signaling.
O

N NH

O

O H N P OO

O P OH OH OH O H

N

N

NH2

-

O

P O-

O H H

a. Gpp(NH)p is a substrate for adenylate cyclase and, thus, will decrease the intracellular concentration of cAMP. b. The G-Gpp(NH)p complex will be deactivated, thereby, decreasing the intracellular concentration of cAMP. c. The G-Gpp(NH)p complex will be activated, thereby, increasing the intracellular concentration of cAMP. d. Gpp(NH)p will stabilize the G, complex, thereby, decreasing the intracellular concentration of cAMP. e. Gpp(NH)p will destabilize the G, complex, thereby, increasing the intracellular concentration of cAMP. 2. Gluconeogenesis must use “bypass reactions” to circumvent three reactions that are highly exergonic and essentially irreversible. Reactions carried out by which three of the enzymes listed must be bypassed in the gluconeogenic pathway? 1) 2) 3) 4) 5) Hexokinase Phosphoglycerate kinase Phosphofructokinase-1 Pyruvate kinase Triosephosphate isomerase

a. b. c. d. e.

1, 2, and 3 1, 2, and 4 1, 3, and 4 2, 3, and 4 2, 4, and 5

1

BCH 3023 – Fall 2008 Final Exam, 12/8/2008
3. The reaction, A + 2B  C, has an equilibrium constant of 1  106 M-2 and a G° of -34.2 kJ/mol. If the concentrations of A, B, and C are all 1.0 mM and the temperature is 25 °C, a. b. c. d. e. the G for the reaction is negative and the reaction will proceed from left to right. the G for the reaction is positive and the reaction will proceed from right to left. the G for the reaction is zero and the reaction is at equilibrium. the G = G° and lnQ = 0. The G = lnQ and G° = 0.

4. For the reaction A  B, G°' = –60 kJ/mol. The reaction is started with 100 mM