Quizzes 19-30

Question 1

How many ATP molecule(s) (including ATP equivalence) is(are) spent on incorporating dietary glucose into glycogen?

Answer 1

2

Question 2

Which enzyme are involved in the regulatory step in glycolysis?

Answer 2

pyruvate kinase, phosphofructose kinase, hexokinase

Question 3

What is a potent activator is phosphofructokinase in mammals?

Answer 3

fructose-2,6-bisphopshate

Question 4

What metabolite cannot be directly converted from pyruvate?

Answer 4

Ethanol

Question 5

What metabolites can be directly converted from pyruvate?

Answer 5

Acetaldehyde, lactate, and acetyl CoA

Question 6

Which glucose transporter is associated with fructose?

Answer 6

GLUT5

Question 7

Assume fructose 1-phosphate is the dominant pathway in naked mole rats, how could fructose metabolism promote resistance to anoxia?

Answer 7

Fructose metabolism avoids feedback inhibition of glycolysis via phosphofructokinase.

Question 8

Describe the Warburg effect?

Answer 8

The enhanced glucose uptake and utilization by cancer cells even in the presence of oxygen.

Question 9

Which step in glycolysis is reversible?

Answer 9

1,3 bisphosphoglycerate + ADP –> 3-phosphoglycerate + ATP

Question 10

The overall reaction of GNG is?

Answer 10

2Pyruvate + 6ATP + 2NADH –> Glucose

Question 11

What will happen to GNG if a starved person becomes drunk? (Challenging!)

Answer 11

Decrease entry of lactate into GNG because the lactate dehydrogenase reaction will be pushed towards the formation of lactate.

Question 12

What is a molecule that cannot be derived from pyruvate directly?

Answer 12

Phosphoenolpyruvate

Question 13

What are some the substrates (s) and products (P) of the TCA cycle?

Answer 13

S = Acetyl-CoA, NAD+, GDP; P = NADH, GTP, CO2.

Question 14

If you begin with a dihydroxyacetone phosphate (DHAP), how many ATP, NADH, FADH2, and CO2 do you end up with at the end of TCA cycle?

Answer 14

3 CO2, 5 NADH, 3 ATP, and 1 FADH2

Question 15

If you start with one molecule of glucose, by the end of TCA cycle, how many ATP, NADH, FADH2 would you have produced?

Answer 15

4 ATP, 10 NADH, 2 FADH2

Question 16

Theoretically, if fumarate is fed into mitochondria, how many ATP molecules should be produced by the end of electron transport chain?

Answer 16

2.5

Question 17

If alanine is fed to cells that are actively carrying out aerobic respiration, how many ATP molecules will cells produce at the end of electron transport chain?

Answer 17

12.5

Question 18

If alanine is fed to cells in the presence of cyanide, how many ATP molecules will cells produce at the end of electron transport chain? Assuming no feedback inhibition.

Answer 18

1

Question 19

Why was there a rise in body temperature in the individuals affected by DNP?

Answer 19

In the presence of DNP, the proton motive force is dissipated as heat.

Question 20

What molecule plays a role in carbohydrate metabolism, but is also essential in fat catabolism?

Answer 20

Acetyl CoA

Question 21

How many ATP molecules are produced when C6:0 fatty acid is catabolized?

Answer 21

36

Question 22

Why would diversifying the fat sources by including odd-chain fatty acids improve a person’s overall metabolic health? Assume this person is on a high fat diet, such as blubber.

Answer 22

Odd-chain fatty acids when broken down provide intermediates that can replenish the TCA cycle and glucoconeogenesis.

Question 23

How many ATP molecules are produced when C5:0 fatty acid is catabolized? (Assuming succinyl CoA goes through TCA cycle)

Answer 23

16

Question 24

What is the reason for liver’s inability to use ketone bodies?

Answer 24

Liver misses CoA transferase.

Question 25

Which of the following is NOT a condition required for ketogenesis? a) Prolonged fasting/starvation b) Increased lipolysis and fatty acid oxidation c) insulin signaling d) depletion of oxaloacetate

Answer 25

c) insulin signaling

Question 26

What molecules plays a role in carbohydrate metabolism, is also essential in fat acid synthesis?

Answer 26

Citrate

Question 27

FADH2 is a common reducing factor that is reoxidized in ETC to produce ATP. Which enzyme does not produce FADH2?

Answer 27

Malic enzyme

Question 28

To synthesize C12:0 fatty acid, how many NADPH molecules are added?

Answer 28

10

Question 29

Which of the following is not a component of the pentose phosphate pathway? a) NADPH b) NADH C) CO2 d) erythrose-4-phosphate

Answer 29

b) NADH

Question 30

In addition to pentose phosphate pathway, which other pathway produces NADPH for fatty acid sytnhesis?

Answer 30

Malic enzyme involved in citrate shuttling

Question 31

What does FAS stand for?

Answer 31

Fatty acid synthesis

Question 32

What metabolite can be used directly to make alanine?

Answer 32

Pyruvate

Question 33

To synthesize a hexapeptide made of alanine, how many glucose molecules do you need?

Answer 33

3

Question 34

During lecture 22 - gluconeogenesis, we mentioned that amino acids Leu and Lys cannot be used to make glucose. What is the reason?

Answer 34

Leu and Lys are broken down to acetoacetate.