HW 10, 11, 12

Question 1

. Which of the following enzymes directly converts phosphorylase b into the more active form, phosphorylase a?

a. adenylate kinase
b. cAMP-dependent protein kinase
c. protein kinase A
d. phosphorylase kinase
e. phosphoprotein phosphatase-1

Answer 1

d) phosphorylase kinase

Question 2

Acetyl-CoA contains a bond which often provides the energy required for substrate-level phosphorylation.

a. phosphoester
b. thioester
c. phosphoanhydride
d. phosphothioester
e. ester

Answer 2

b. thioester

Question 3

. Increased levels of epinephrine in the blood will
I. increase cAMP in liver and muscle cells
II. stimulate glycogen synthesis
III. inhibit glycolysis in the muscle cell
IV. stimulate gluconeogenesis in the muscle cell

a. I, II, III
b. I, II
c. I only
d. II only
e. I, II, III, IV

Answer 3

c. I only

Question 4

Which of the following coenzymes is required by E1 of the pyruvate dehydrogenase complex for catalytic activity?

a. thiamine pyrophosphate
b. lipoamide
c. coenzyme A
d. NAD+
e. FAD

Answer 4

a. thiamine pyrophosphate

Question 5

E2 of the pyruvate dehydrogenase complex contains a lipoyl group that is covalently attached via an amide linkage to a residue on the enzyme

a. arginine
b. tyrosine
c. serine
d. lysine
e. cysteine

Answer 5

d. lysine

Question 6

. If cAMP levels are high
I. Glycogenolysis will occur in muscle cells but not in liver cells
II. Glucose released from muscle glycogen will enter glycolysis
III. Glucose released from liver glycogen will exit liver cells via the GLUT4 transporter
IV. Glucose will enter liver cells resulting in glycogen synthesis

a. II only
b. I, II, IV
c. I, II
d. II, III, IV
e. III only

Answer 6

a. II only

Question 7

How many NADH are produced when one acetyl group is oxidized in the citric acid cycle?

a. 1
b. 3
c. 2
d. 4
e. 5

Answer 7

b. 3

Question 8

Which of the following will NOT activate glycogen phosphorylase in the liver?

a. cAMP
b. epinephrine
c. glucagon
d. eating a high carbohydrate meal

Answer 8

d. eating a high carbohydrate meal

Question 9

Which of the following uses inherent length and flexibility to facilitate transfer of an acetyl group?

a. lipoamide
b. FAD
c. NAD+
d. thiamine pyrophosphate
e. coenzyme A

Answer 9

a. lipoamide

Question 10

Which of the following coenzymes is required by the pyruvate dehydrogenase complex for reoxidation of E3?

a. pyridoxal phosphate
b. thiamine pyrophosphate
c. NAD+
d. coenzyme A
e. FAD

Answer 10

a. NAD+

Question 11

Condensation of _____ with oxaloacetate yields citrate.

a. alpha-ketoglutarate
b. acetyl-CoA
c. isocitrate
d. citrophosphate
e. oxalosuccinate

Answer 11

b. acetyl-CoA

Question 12

The reaction catalyzed by ____ requires an enzyme bound flavin coenzyme.

a. malate dehydrogenase
b. isocitrate dehydrogenase
c. alpha-ketoglutarate dehydrogenase
d. succinyl-CoA synthetase
e. succinate dehydrogenase

Answer 12

e. succinate dehydrogenase

Question 13

Which of the following utilizes intermediates of the citric acid cycle?
	I. gluconeogenesis
	II. amino acid biosynthesis
	III. fatty acid oxidation
	IV. glycolysis

a. I, II, III
b. I only
c. I, II
d. II only
e. I, IV

Answer 13

c. I, II

Question 14

Which of the following enzymes of the citric acid cycle is inhibited by ATP?

a. isocitrate dehydrogenase
b. citrate synthase
c. alpha-ketoglutarate dehydrogenase
d. succinyl-CoA synthetase

Answer 14

a. isocitrate dehydrogenase

Question 15

Which of the following organisms does not utilize the glyoxylate cycle?

a. mammals
b. trees
c. bacteria
d. fungi

Answer 15

a. mammals

Question 16

Which of the following would decrease activity of the citric acid cycle overall?
	I. high concentration of NADH
	II. high concentration of Ca2+
        III. high concentration of ATP
	IV. high concentration of citrate

a. I, IV
b. I only
c. I, II, III, IV
d. I, III
e. I, III, IV

Answer 16

e. I, III, IV

Question 17

. Which of the following citric acid cycle intermediates can be converted to aspartate via transamination?

a. citrate
b. oxaloacetate
c. alpha-ketoglutarate
d. succinate
e. fumarate

Answer 17

b. oxaloacetate

Question 18

. Which of the following represents a point of regulation for the citric acid cycle?
	I. pyruvate dehydrogenase complex
	II. aconitase
        III. isocitrate dehydrogenase
	IV. fumarase

a. I, II, III, IV
b. I, II, IV
c. I, III
d. II, III
e. I, IV

Answer 18

c. I, III

Question 19

Calculate E°’ for the reduction of ubiquinone (standard reduction potential is 0.045 V) by NADH (standard reduction potential is -0.315 V). Your answer should be in V to the nearest hundredths (do not include units).

Answer 19

0.36

Question 20

Calculate G°’ for the above reaction. Faraday’s constant is 96,485 Jmol-1V-1. Your answer should be in J/mol to the nearest hundredths (do not include units).

Answer 20

-69,469.2

Question 21

Is the reaction above spontaneous? Answer Yes or No.

Answer 21

Yes

Question 22

While ___ is always involved in reactions that require the transfer of 2 electrons, ___can participate in reactions that transfer either 1 or 2 electrons.

a. NAD+; FAD
b. O2; NAD+
c. NAD+; O2
d. flavin; niacin
e. FAD; NAD+

Answer 22

a. NAD+; FAD

Question 23

Approximately how many ATP molecules are synthesized from the oxidation of 1 NADH?

a. 1.5
b. 1
c. 2.5
d. 2
e. 3

Answer 23

c. 2.5

Question 24

In redox half-reactions, a more positive standard reduction potential means
I. the oxidized form has a higher affinity for electrons
II. the oxidized form has a lower affinity for electrons
III. the reduced form has a higher affinity for electrons
IV. the greater the tendency for the oxidized form to accept electrons

a. II, IV
b. I only
c. II only
d. II, III
e. I, IV

Answer 24

e. I, IV

Question 25

Which of the prosthetic groups listed can accept or donate either one or two electrons due to the stability of the semiquinone state? a. cytochrome c b. CoQ c. NADH d. [2Fe-2S] e. Rieske center

Answer 25

b. CoQ

Question 26

In the electron transport chain, electrons are passed from redox center to redox center . a. as a result of the addition of free energy b. in an ATP dependent fashion c. spontaneously due to the redox potential gradient d. as a result of the proton gradient e. with the assistance of a carrier protein

Answer 26

c. spontaneously due to the redox potential gradient

Question 27

The electrons formed from the aerobic oxidation of glucose are I. ultimately transferred to O2 after several other transfer reactions II. transferred to the coenzymes NAD+ and FAD III. directly transferred to O2 during the citric acid cycle IV. transferred to succinate and arachidonic acid a. I, II, III b. I only c. II only d. II, III, IV e. I, II

Answer 27

e. I, II

Question 28

Electrons from FADH2 are delivered to ____ and electrons from NADH are delivered to____ of the electron transport chain. a. Complex III; Complex I b. Complex II; Complex I c. Complex I; Complex II d. Complex II; Complex III e. Complex I; Complex IV

Answer 28

b. Complex II; Complex I