There are 24 questions in all. Questions 1-20 are multiple choice and are each worth 3 points. Questions 21-24 are essays and problems worth a total of 40 points.

Constants: R = 8.314 J/mole-K; T = 298 K; F = 96480 J/V-mol
             ΔG°′ for ATP + H₂O → ADP + P_i is − 30.5 kJ/mol

              1. The epinephrine receptor binds

A receptor exposed to all three at the same time will be                    for a                     time until                           dissociates.
(A) inhibited, short, isoproteronol; (B) activated, long, epinephrine;
(C) inhibited, long, propanolol; (D) inhibited, long, isoproteronol.

              2. Both the Ca²⁺ ATPase and the Na⁺–K⁺ ATPase are P-type ATPases. This means that both (A) transfer phosphate as well as their specified ion(s) across the membrane;
(B) are ion channels that open when they are phosphorylated;
(C) transfer a phosphoryl group to an Asp residue and change conformation;
(D) form an ATP-cation complex that is transported across the membrane.

              3. Which of the following co-transporters is a symport? We haven't studied these, but all of them use diffusion only (no active transport).
(A) H⁺–H₂PO₄⁻; (B) Cl⁻–HCO₃⁻; (C) Ca²⁺–Na⁺; (D) Asp–Glu.

              4. A graph of the rate of solute transport with increasing [solute] for the transporters in question 3 is a (A) hyperbolic graph because the transporters are channels;
(B) hyperbolic graph because the transporters change conformation;
(C) sigmoidal graph because the solutes bind cooperatively;
(D) straight line graph because the transporters have a high rate of flux.

              5. There are many different G proteins. All of them convert GTP to GDP by
(A) transferring a phosphoryl group to a second messenger; (B) hydrolysis;
(C) transferring a phosphoryl group to adenylyl cyclase (AC);
(D) reversible phosphorylation of the βγ subunits.

              6. Adenylyl cyclase (AC) produces                      , which are degraded by                         , respectively. (A) cAMP and PP_i, PKA and phosphodiesterase;
(B) GDP and P_i, NDP kinase and no enzyme needed;
(C) cAMP and PP_i, cyclic phosphodiesterase and pyrophosphatase;
(D) cAMP and P_i, two different hydrolases.

              7. If two G_sα proteins are activated, and each AC activated as a result catalyzes its reaction 12 times, what is the maximum number of active PKA's that can result?
(A) 24; (B) 48; (C) 12; (D) 6.

              8. Converting FBP ↔ GAP + DHAP has ΔG°′ = 23.8 kJ/mol in the direction written. This is, however, one of the reversible reactions of both glycolysis and gluconeogenesis. This means that in a liver cell
(A) the reaction is coupled to ATP hydrolysis; (B) [FBP] > ([GAP] + [DHAP]);
(C) ([GAP] + [DHAP]) > [FBP]; (D) [FBP]   > ([GAP] [DHAP]) .
FBP = fructose-1,6-bis-P; GAP = glyceraldehyde-P; DHAP = dihydroxyacetone-P.

Use these values for question 9.

              9. Some ligases convert ATP to AMP + PP_i. Converting AMP + PP_i back to ATP requires ATP synthase and the enzyme(s)               for a total ΔG°′ =                         .
(A) NDP kinase and pyrophosphatase, + 19 kJ/mol;
(B) adenylate kinase, + 30.5 kJ/mol;
(C) adenylate kinase and pyrophosphatase, + 51 kJ/mol;
(D) adenylate kinase and NDP kinase, + 30.5 kJ/mol.

              10. Which of the following is an oxidation half reaction?
(A) malic acid → malate + 2 H⁺; (B) malate + 2 H⁺ → malic acid;
(C) malate → oxaloacetate + 2 H; (D) oxaloacetic acid + 2 H → malic acid.

              11. In the preparation phase of glycolysis            ATP are used by                                     .
(A) 2, ligases to break glucose into 2 glycerols;
(B) 2, ligases to break glucose into 2 glyceraldehyde-P's;
(C) 2, kinases to phosphorylate hexoses that are split into isomers;
(D) 4, kinases to phosphorylate glucose + fructose to make 2 molecules of 1,3-BPG.

              12. The reaction catalyzed by pyruvate kinase requires                  as a substrate, releases                          as the first product, and converts the intermediate                                .
(A) pyruvate, PEP, ATP → ADP; (B) PEP, ATP, enolpyruvate → pyruvate;
(C) pyruvate, ADP, phosphopyruvate → PEP; (D) PEP, pyruvate, ADP → ATP.

              13. When the pentose phosphate pathway is used to provide energy for fat synthesis,
               xylulose-5-P →                                                                 .
(A) one, one ribose-5-P; (B) two, one fructose-6-P + one glyceraldehyde-P;
(C) three, two fructose-6-P + one glyceraldehyde-P; (D) five, six fructose-6-P.

14-17. Use these enzymes: (A) alcohol dehydrogenase; (B) lactate dehydrogenase;
(C) pyruvate decarboxylase; (D) pyruvate carboxylase; (G) glucose-6-P dehydrogenase.

Use these coenzyme changes: (M) NAD⁺ → NADH; (N) NADH → NAD⁺;
(O) NADP⁺ → NADPH; (P) NADPH → NADP⁺; (R) ATP → ADP; (S) ADP → ATP;
(T) TPP which doesn't change; (U) biotin which doesn't change.

Write 2 letters for each reaction: one (A–E) for the enzyme and one (M–U) for the coenzyme.

18-19. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) catalyzes a reversible reaction.

              18. This reaction (A) is a ping-pong reaction in which NADH is the 1^st product;
(B) involves forming a ternary complex, and NADH is the 1^st product;
(C) is a ping-pong reaction in which ATP is the 2^nd substrate;
(D) involves forming a ternary complex in which ATP is the 2 nd product.

              19. During gluconeogenesis, GAPDH converts (A) ATP to ADP; (B) ADP to ATP;
(C) NAD⁺ to NADH; (D) NADH to NAD⁺.

              20. The preparation phase of glycolysis has an energy cost of                   ATP and a total energy yield of                 ATP +                   NADH per glucose.
(A) 2, 4, 2; (B) 2, 0, 0; (C) 2, 2, 2; (D) 0, 4, 2.

21. Cytosolic [Ca²⁺] is normally less than 1 µM. SR (sarcoplasmic reticulum) [Ca²⁺] is normally 300 µM, although under some conditions it increases. Assume the membrane potential for the SR membrane is ΔV = − 0.040 V (SR → cytosol).
ΔG_T = R T ln (C₂/C₁) + Z F ΔV

a. Calculate ΔG_T for moving Ca²⁺ into the SR using the Ca²⁺ ATPase, which moves 2 Ca²⁺
      for each cycle.
b. Based upon your answer to part (a), how many Ca²⁺ can be moved into the
     organelle per mole ATP hydrolyzed by the Ca²⁺ ATPase?
c. What happens to both of your answers when SR [Ca²⁺] is doubled? And what effect
      might this change in concentration have on ?V?

22. The nicotinic acetylcholine (ACh) receptor is a gated ion channel that is also involved in
biosignaling.
a. What amino acid is an important feature of the "gate", and what happens to it when
      the gate opens?
b. List three of the characteristics of biosignaling pathways. Read part c first.
c. Explain how the nicotinic ACh receptor illustrates two of the characteristics you listed.

23. The half reactions below are part of electron transport, which we study next.
cyt c is a protein (cytochrome c) that contains heme with Fe.

a. Write the balanced spontaneous whole reaction.
b. Calculate ΔE°′ and ΔG°′ for the spontaneous whole reaction.
c. How many ATP's could theoretically be synthesized using the energy from this
     oxidation-reduction reaction?

24. Glycolysis and gluconeogenesis use many of the same enzymes, but irreversible reactions require different enzymes. Use the table for parts a and b.
Please read the questions carefully and answer only what is asked.
a. Name two enzymes that catalyze irreversible reactions in glycolysis.
b. Name the enzymes that catalyze reactions in gluconeogenesis that reverse the
      glycolysis enzymes you listed in a. If two enzymes are required, you must list both.
c. For each of the reactions you listed, what is the energy gain or loss?

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