Module 8

Question 1

The biggest energy reserve in a healthy human is:

Answer 1

triacylglycerols in adipose tissue.

Question 2

During fermentation, the conversion of 2 moles of glucose to 4 moles of lactic acid is accompanied by a net yield of:

Answer 2

4 moles of ATP.

Question 3

Why is lactate production low when muscles contract under aerobic conditions?

Answer 3

under aerobic conditions most of the pyruvate generated as a result of glycolysis is oxidized by the citric acid cycle rather than reduced to lactate.

Question 4

How do the catabolic products of fatty acid oxidation enter the TCA cycle?

Answer 4

acetyl CoA

Question 5

What happens to the heat that is produced when an organism engages in mechanical work?

Answer 5

It is lost to the environment.

Question 6

Predict what will happen when thermogenin production goes up in the brown fat cells?

Answer 6

ATP synthesis will decrease, and heat generation will increase.

Question 7

An electron experiences a loss of potential energy when it:

Answer 7

moves to a more electronegative atom.

Question 8

Describe what is happening in the reaction: Glucose + 6 O2 → 6 CO2 + 6 H2O + Energy:

Answer 8

C6H12O6 is oxidized and O2 is reduced.

Question 9

The glycolytic production of ATP involves:

Answer 9

substrate-level phosphorylation.

Question 10

At which step/ process of cellular respiration is oxygen required?

Answer 10

accepting electrons at the end of the electron transport chain

Question 11

What is the path taken by electrons inside an active mitochondria?

Answer 11

TCA → NADH → ETC → oxygen

Question 12

What drives ATP production via oxidative phosphorylation?

Answer 12

energy released from movement of protons down their gradient through ATP synthase

Question 13

ETC pumps protons into which location?

Answer 13

mitochondrial intermembrane space

Question 14

Which of these chemicals would immediately stop glycolysis? A chemical that

Answer 14

closely mimics the structure of glucose but is not metabolized

Question 15

During the conversion of glucose to carbon dioxide and water, which stage results in maximal production of ATP?

Answer 15

oxidative phosphorylation

Question 16

What does proton motive force refer to?

Answer 16

transmembrane proton concentration gradient

Question 17

Which of these is true regarding glycolysis?

Answer 17

It is found in the cytosol, does not involve oxygen, and is present in most organisms.

Question 18

What happens to lactate that is produced from pyruvate?

Answer 18

It will be converted back to pyruvate.

Question 19

The free energy for the oxidation of glucose to carbon dioxide and water is approximately -700 kilocalories per mole and the free energy for the reduction of NAD+ to NADH is +50 kilocalories per mole. Why are only two molecules of NADH formed during glycolysis when it appears that more than a dozen could be formed?

Answer 19

Most of the free energy available from the oxidation of glucose remains in pyruvate.

Question 20

Describe how the rate of glycolysis is adjusted to meet the cell’s need for ATP. What are the key regulatory enzymes involved and to what regulators do they respond to?

Answer 20

Hexokinase: glucose 6-phosphate
Pyruvate kinase: ATP
Phosphofructokinase-1: activated by AMP and fructose 2,6-bisphosphate, inhibited by ATP

Question 21

What are the underlying reason for the difference in ATP yield for electrons donated by FADH2 and NADH?

Answer 21

Complex II is not a pump

Question 22

Discuss the interrelationships between anabolic and catabolic pathways. Provide specific examples in your answer.

Answer 22

ATP powers anabolic reactions, ATP is produced by catabolic reactions

Question 23

The four stages of glucose oxidation are listed below. Place them in the correct order.

Answer 23

c. conversion in the cytosol of one 6-carbon glucose molecule to two 3-carbon pyruvate molecules
a. pyruvate oxidation to CO2in the mitochondrion via a 2-carbon acetyl CoA intermediate
b. electron transport to generate a proton motive force
d. ATP synthesis in the mitochondrion (oxidative phosophorylation).

Question 24

During prolonged exercise, oxygen is scarce in muscle tissue. Under these conditions, muscle cells convert pyruvate to two molecules of lactic acid. Explain why, and what happens to the lactic acid that is generated in this way?

Answer 24

Regenerates NAD+

Question 25

Explain how proton motif force is generated in mitochondria and chloroplasts.

Answer 25

ETC pumps protons