Please answer all questions by bubbling in on the Answer Sheet, the BEST possible lettered answer.
1. All receptor enzymes:
a. act by phosphorylating cAMP. b. alter gene expression
c. have their active sites on the cytosolic side of the plasma membrane.
d. consist of more than one subunit. e. all of the above.
2. G-protein receptors:
a. have a single transmembrane domain. b. are ion channels. c. act in the nucleus.
d. have enzymatic activity. e. generate second messengers.
3. Which of the following occurs in a cell as a result of insulin binding to its receptor? a.
Glycogen synthase becomes activated. b. Glucose is released from the cell.
c. The glucose transporter GLUT4 moves from the plasma membrane to internal membrane vesicles. d. Cyclic
GMP is produced. e. Cyclic AMP is produced.
4. Activation of a G protein-coupled receptor causes stimulatory G protein (Gs) to:
a. replace its bound GDP with GTP. b. dissociate from adenylyl cyclase.
c. hydrolyze GTP into GDP and Pi. d. generate cGMP. e. all of the above.
5. A chemical reaction is more likely to occur spontaneously if:
a. the products of the reaction are more complex than the reactants.
b. the system takes up heat from its surroundings. c. the system gains free energy.
d. the products of the reaction are more disordered than the reactants.
6. If a chemical reaction starts with 1M concentrations each of reactants A and B and products C and D, under what
conditions of Keq and ∆G’° will the reaction proceed in the forward direction (∆G’° = -RT ln K eq)?
a. If Keq is greater than 1 and ∆G’° is negative. b. If K eq is 0 and ∆G’° is negative.
c. If Keq is negative and ∆G’° is negative. d. If Keq is less than 1 and ∆G’° is positive.
7. Which of the following has a thioester bond?
a. Phosphoenolpyruvate. b. ATP. c. phosphocreatine. d. acetyl-CoA. e. NADH.
8. Which of the following carbon-containing molecules is most fully oxidized?
a. carbon monoxide. b. carbon dioxide. c. methane. d. ethanol. e. pyruvate.
9. Electrons can be transferred from one molecule (electron donor) to another molecule (electron acceptor) by all of the
following ways except:
a. as a hydride ion. b. directly as an electron. c. as a proton. d. as a hydrogen atom.
e. none of the above.
10. Below are the standard reduction potentials (E’°) for two conjugate redox pairs:
Pyruvate -/lactate- E’° = –0.185v NAD+/NADH E’° = –0.320v Which of the following is
true?
a. The pyruvate/lactate conjugate redox pair has a greater tendency to lose electrons than the
NAD+/NADH redox pair.
b. Pyruvate has a greater affinity for electrons than NAD+. c. NAD+ is a reducing agent.
d. Under standard conditions, NAD+ is more likely to be converted to NADH, than pyruvate is to be converted
to lactate. e. none of the above.
1. All receptor enzymes:
a. act by phosphorylating cAMP. b. alter gene expression
c. have their active sites on the cytosolic side of the plasma membrane.
d. consist of more than one subunit. e. all of the above.
2. G-protein receptors:
a. have a single transmembrane domain. b. are ion channels. c. act in the nucleus.
d. have enzymatic activity. e. generate second messengers.
3. Which of the following occurs in a cell as a result of insulin binding to its receptor? a.
Glycogen synthase becomes activated. b. Glucose is released from the cell.
c. The glucose transporter GLUT4 moves from the plasma membrane to internal membrane vesicles. d. Cyclic
GMP is produced. e. Cyclic AMP is produced.
4. Activation of a G protein-coupled receptor causes stimulatory G protein (Gs) to:
a. replace its bound GDP with GTP. b. dissociate from adenylyl cyclase.
c. hydrolyze GTP into GDP and Pi. d. generate cGMP. e. all of the above.
5. A chemical reaction is more likely to occur spontaneously if:
a. the products of the reaction are more complex than the reactants.
b. the system takes up heat from its surroundings. c. the system gains free energy.
d. the products of the reaction are more disordered than the reactants.
6. If a chemical reaction starts with 1M concentrations each of reactants A and B and products C and D, under what
conditions of Keq and ∆G’° will the reaction proceed in the forward direction (∆G’° = -RT ln K eq)?
a. If Keq is greater than 1 and ∆G’° is negative. b. If K eq is 0 and ∆G’° is negative.
c. If Keq is negative and ∆G’° is negative. d. If Keq is less than 1 and ∆G’° is positive.
7. Which of the following has a thioester bond?
a. Phosphoenolpyruvate. b. ATP. c. phosphocreatine. d. acetyl-CoA. e. NADH.
8. Which of the following carbon-containing molecules is most fully oxidized?
a. carbon monoxide. b. carbon dioxide. c. methane. d. ethanol. e. pyruvate.
9. Electrons can be transferred from one molecule (electron donor) to another molecule (electron acceptor) by all of the
following ways except:
a. as a hydride ion. b. directly as an electron. c. as a proton. d. as a hydrogen atom.
e. none of the above.
10. Below are the standard reduction potentials (E’°) for two conjugate redox pairs:
Pyruvate -/lactate- E’° = –0.185v NAD+/NADH E’° = –0.320v Which of the following is
true?
a. The pyruvate/lactate conjugate redox pair has a greater tendency to lose electrons than the
NAD+/NADH redox pair.
b. Pyruvate has a greater affinity for electrons than NAD+. c. NAD+ is a reducing agent.
d. Under standard conditions, NAD+ is more likely to be converted to NADH, than pyruvate is to be converted
to lactate. e. none of the above.
