Q: Which of the following reactions is catalyzed by pyruvate dehydrogenase?

$$\text{Pyruvate} + \text{NAD}^+ + \text{CoA} \rightarrow \text{Acetyl-CoA} + \text{CO}_2 + \text{NADH}$$

Q: Which step in the citric acid cycle directly produces GTP (or ATP)?

$$\text{Succinyl-CoA} \rightarrow \text{Succinate}$$

Question 1

Which statement best describes the difference between the lock-and-key model and the induced fit model of enzyme-substrate binding?

Accepted Answer

The lock-and-key model suggests a rigid fit between enzyme and substrate, while the induced fit model suggests the enzyme's active site molds itself around the substrate upon binding.

Question 2

Which of the following best describes the role of a coenzyme in an enzymatic reaction?

Accepted Answer

A coenzyme is a non-protein molecule that temporarily binds to the enzyme to assist in the transfer of specific atoms or functional groups during the reaction.

Question 3

Which of the following would most likely increase the rate of an enzyme-catalyzed reaction?

Accepted Answer

Increasing substrate concentration until the enzyme becomes saturated.

Question 4

Which equation correctly represents the relationship between enzyme activity and substrate concentration at low substrate levels?

Accepted Answer

$$v = \frac{V_{max} \cdot [S]}{K_m + [S]}$$

Question 5

Which statement best distinguishes between competitive and noncompetitive enzyme inhibition?

Accepted Answer

Competitive inhibitors compete with the substrate for the active site, while noncompetitive inhibitors bind elsewhere and change the enzyme's shape.

Question 6

Which of the following is an example of a catabolic pathway?

Accepted Answer

Glycolysis, which breaks down glucose to pyruvate.

Question 7

During glycolysis, what is the fate of pyruvate under anaerobic conditions in muscle cells?

Accepted Answer

It is reduced to lactate to regenerate NAD$$^+.$$

Question 8

Which of the following reactions is catalyzed by pyruvate dehydrogenase?

Accepted Answer

$$	ext{Pyruvate} + 	ext{NAD}^+ + 	ext{CoA} ightarrow 	ext{Acetyl-CoA} + 	ext{CO}_2 + 	ext{NADH}$$

Question 9

Which step in the citric acid cycle directly produces GTP (or ATP)?

Accepted Answer

$$	ext{Succinyl-CoA} ightarrow 	ext{Succinate}$$

Question 10

Which molecule acts as the final electron acceptor in the electron transport chain?

Accepted Answer

O$$_2$$

Question 11

How many ATP molecules are produced from the complete aerobic oxidation of one molecule of glucose?

Accepted Answer

32

Question 12

Which of the following statements about fatty acid oxidation is correct?

Accepted Answer

Fatty acids are transported into the mitochondria and oxidized via beta-oxidation to produce acetyl-CoA.

Question 13

If a fatty acid contains 18 carbons, how many rounds of beta-oxidation are required to completely oxidize it?

Accepted Answer

8

Question 14

Which of the following is a glucogenic amino acid?

Accepted Answer

Alanine

Question 15

Which process describes the conversion of non-carbohydrate precursors into glucose?

Accepted Answer

Gluconeogenesis

Question 16

Which of the following best explains why fatty acids yield more ATP than carbohydrates upon complete oxidation?

Accepted Answer

Fatty acids are more reduced, allowing for more electron transfer and ATP generation during oxidation.

Question 17

Which of the following is true regarding the Cori cycle?

Accepted Answer

It converts lactate produced in muscles back to glucose in the liver.

Question 18

Which of the following is a product of the reaction catalyzed by succinate dehydrogenase in the citric acid cycle?

Accepted Answer

Fumarate

Question 19

Which equation represents the net reaction of glycolysis?

Accepted Answer

$$	ext{Glucose} + 2 	ext{NAD}^+ + 2 	ext{ADP} + 2 	ext{P}_i ightarrow 2 	ext{Pyruvate} + 2 	ext{NADH} + 2 	ext{ATP} + 2 	ext{H}_2	ext{O}$$

Metabolism, Enzymes, and Bioenergetics: GOB Chemistry Study Guide

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