CHEM 423B Study Guide - Quiz Guide: Succinyl-Coa, Malate Dehydrogenase, Acetyl-Coa

1. Which is an w-3 fatty acid?

A) B) C) D) E) None ofthese

2. In many cases, cellular signal transduction is mediated by amembrane-associated G-protein complex. Which is not right aboutthis protein complex?

A) The complex is made of α-, β-, and γ-subunit.

B) The G_sα-subunit has a GTPase activity.

C) Depending on the receptor types, eitherG_sα-subunit or G_iα-subunit is used.

D) Signal transduction through G-proteins ultimately regulatesprotein phosphorylation.

E) None of the above.

3. Which statement is not right about the pyruvatedehydrogenase?

A) This enzyme is located in the mitochondria.

B) This enzyme consists of three different enzymatic subunits(E1, E2, and E3).

C) This enzyme catalyzes the reaction: Pyruvate + CoA + NAD ®Acetyl-CoA + CO₂ + NADH

D) This enzyme also uses TPP (thiamine pyrophosphate), lipoicacid, and FAD as cofactors.

E) Despite its complexity, this enzyme is not an importantregulation point of TCA cycle.

4. To maintain a proper rate of the TCA cycle, oxaloacetate isreplenished periodically. To increase [oxaloacetate], ___X____ isturned on but the rest step of TCA cycled is turned off byphosphorylation of __Y__.

A) X = Glyoxylate cycle :::::: Y = isocitrate dehydrogenase

B) X = Glyoxylate cycle :::::: Y = isocitrate lyase

C) X = Qcycle :::::: Y = isocitrate dehydrogenase

D) X = Qcycle :::::: Y = isocitrate lyase

E) None of the above.

5. Assume you have three NADH and one FADH₂.Calculate the total numbers of H⁺ pumped into theinter-membrane space and the maximal number of ATP produced insidethe matrix.

A) 40 H⁺ and 12 ATP
B) 40 H⁺ and 11 ATP
C) 36 H⁺ and 12 ATP

D) 36 H⁺ and 11 ATP
E) None of the above.

I put the following

1. D

2. D

3. E.

4. idk

5. idk

Can someone help me out for 4 & 5 and reassure I got 1-3correct! Thanks

1. Oxygen atoms present in CO2 that is released in the Kreb's cyclecome from-

a. Molecular oxygen (O2)
b. Acetyl CoA
c. H2O
d. Acetyl CoA and H2O
e. NADH + H+

2. How many ATP are obtained by substrate-level phosphorylationduring a complete oxidation of a single glucose molecule (includeGlycolysis, PDH reaction and the Krebs' cycle, do NOT subtract"energy investment")

a. 1
b. 2
c. 4
d. 6
e. 32

3. One of the differences between the isocitrate dehydrogenasereaction and the alpha-ketoglutarate dehydrogenase reactionis:

a. only one of them is an oxidative decarboxylation reaction
b. only one of them uses CoA-SH as the source for one electron(hydrogen)
c. only one of them uses NAD+ as the electron (hydrogen)carrier
d. only one of them requires ATP
e. only one of them yields ATP (or GTP)

4. Which of the following would most likely act as an inhibitor ofthe enzymes of the citric acid cycle?

a. high concentration of ADP
b. high concentration of ATP
c. high concentration of NADH
d. high concentration of NAD+
e. more than one of the above

1. C6H12O6 + 6O2 Ã 6CO2 + 6H2O Glucose is being _____ to _____ and oxygen is being _____ to _____. a. oxidized; carbon dioxide; reduced; water b. oxidized; water; reduced; carbon dioxide Incorrect c. reduced; water; oxidized; carbon dioxide d. reduced; carbon dioxide; oxidized; water

2. Which of the following stages in the breakdown of the piece of toast you had for breakfast generates the most ATP? a. the citric acid cycle Incorrect b. glycolysis c. the digestion of starch to glucose d. oxidative phosphorylation

3. Which of the following is a catabolic pathway? a. gluconeogenesis b. production of starch Incorrect c. glycolysis d. production of glycogen

4. Per molecule, the oxidation of a fatty acid results in _____ energy storage than the oxidation of glucose. a. the same b. less Incorrect c. more d. None of the above; fatty acids cannot be oxidized.

5. Of the eight reactions in the citric acid cycle, how many are oxidation-reduction reactions? a. one b. two c. three d. four e. five

6. The process of glycolysis transfers the energy in sugar molecules into the stored energy of activated carriers such as ATP and NADH. Which statement is true about glycolysis? a. Only eukaryotic organisms do glycolysis. b. The ten reactions of glycolysis are identical in all eukaryotic cells, but are different in prokaryotic cells due to their diverse metabolic strategies. Incorrect c. The ten reactions of glycolysis are identical in almost all living organisms on the planet. d. There are many ways to oxidize glucose and transfer energy into activated carriers; the diversity of organisms on the planet is reflected in the diversity of their mechanisms of glycolysis.

7. Referring to the sentence completed in #13 above, the purpose of the latter reaction (in active muscle cells) is to _____. a. accumulate lactic acid in the cell, which provides additional energy for the production of ATP Incorrect b. slow down glycolysis until oxygen becomes available again c. accelerate the Krebs cycle, which will restore the oxygen supply d. regenerate NAD+ so that glycolysis can continue in the absence of oxygen

8. What are the products of the citric acid cycle? a. carbon dioxide, NADH, FADH2 and GTP b. carbon dioxide, NAD+, FAD and GTP c. NADH, FADH2, and acetyl CoA Incorrect d. carbon dioxide and water

9. Which statement is true about enzymes? a. Enzymes catalyze chemical reactions because they make inherently endergonic reactions exergonic. b. Each enzyme in a cell can catalyze many different chemical reactions involving chemically different substrates. Incorrect c. Enzymes can only catalyze reactions in one direction. d. After catalyzing a reaction, an enzyme is permanently altered and can no longer bind substrate. e. None of the above is true. 1

10. ∆G measures the change in free energy in a system as it converts reactant (Y) into product (X). When [X] = [Y], ∆G is equal to _____. a. RT b. ΔG° + RT c. ΔG° d. ln [X]/[Y]

11. The ∆G° for the hydrolysis of ATP is -7.3 kcal/mol. What conditions in the cell would lead to a ∆G for ATP hydrolysis of -11 kcal/mol? a. An increase in the ATP/ADP ratio b. An increase in anabolic activity in the cell c. Transport of ATP out of the compartment where the reaction is occurring Incorrect d. A decrease in the ATP/ADP ratio

12. In the first reaction of glycolysis, a phosphate transferred from ATP to a glucose molecule to produce glucose-6-phosphate and ADP. Under conditions existing in the cell, the free energy change for this reaction is -8.0 kcal/mole. Which of the following statements is true? Recall that the ∆G° for the hydrolysis of ATP is -7.3 kcal/mol. a. Glucose concentrations in the cell are always low, making this reaction more favorable than would be expected. b. This reaction is less favorable than would be expected, given the ∆G° of ATP hydrolysis. c. Glucose-6-P concentrations in the cell are very low relative to glucose concentrations, making the reaction more favorable than would be expected. d. The ∆G° for the addition of a phosphate to glucose must be -0.7 kcal/mole.

13. Protein E can bind to two different proteins, S and I. The binding reactions are described by the following equations and values: E + S --> ES Keq for ES = 10 E + I> EI Keq for EI = 2 Given the equilibrium constant values, which one of the following statements is true? a. When S is present in excess, no I molecules will bind to E. b. E binds I more tightly than S. c. The binding energy of the ES interaction is greater than that of the EI interaction. d. Changing an amino acid on the binding surface of I from a basic amino acid to an acidic one will probably make the free energy of association with E more negative.