$$\text{fatty acid} + ATP + HS\text{-}CoA \rightarrow \text{acyl-CoA} + AMP + 2 Pi$$

Question 1

Which of the following statements best explains why fats yield more energy per gram than carbohydrates upon oxidation?

Accepted Answer

Fats contain more carbon and hydrogen relative to oxygen, allowing for more oxidation steps.

Question 2

A patient with a deficiency in carnitine acyltransferase I would most likely experience which metabolic consequence?

Accepted Answer

Impaired transport of long-chain fatty acids into the mitochondrial matrix for β-oxidation.

Question 3

Which hormone(s) stimulate the release of fatty acids from adipose tissue during fasting?

Accepted Answer

Epinephrine and glucagon

Question 4

During β-oxidation of palmitoyl-CoA ($$C_{16}$$), how many rounds of β-oxidation are required and how many acetyl-CoA molecules are produced?

Accepted Answer

$$7$$ rounds, $$8$$ acetyl-CoA

Question 5

Which of the following best describes the role of malonyl-CoA in fatty acid metabolism?

Accepted Answer

It inhibits carnitine acyltransferase I, preventing fatty acid entry into mitochondria.

Question 6

A person with type I diabetes is at risk for diabetic ketoacidosis because:

Accepted Answer

Lack of insulin leads to increased fatty acid breakdown and excess ketone body formation.

Question 7

Which of the following is a correct summary equation for the activation of a fatty acid before β-oxidation?

Accepted Answer

$$	ext{fatty acid} + ATP + HS	ext{-}CoA ightarrow 	ext{acyl-CoA} + AMP + 2 Pi$$

Question 8

Which of the following is NOT a function of lipoproteins?

Accepted Answer

Direct catalysis of fatty acid β-oxidation

Question 9

Aspirin reduces inflammation primarily by inhibiting which enzyme involved in eicosanoid synthesis?

Accepted Answer

Cyclooxygenase

Question 10

Which of the following statements about cholesterol biosynthesis is TRUE?

Accepted Answer

The rate-limiting step is catalyzed by HMG-CoA reductase.

Question 11

Which lipoprotein is primarily responsible for reverse cholesterol transport from tissues to the liver?

Accepted Answer

HDL

Question 12

A patient with Lesch-Nyhan syndrome is deficient in which enzyme, leading to neurological symptoms and gout?

Accepted Answer

Hypoxanthine-guanine phosphoribosyltransferase (HGPRT)

Question 13

Which of the following is a direct product of the β-oxidation of odd-chain fatty acids?

Accepted Answer

Propionyl-CoA

Question 14

Which of the following drugs is a competitive inhibitor of xanthine oxidase and used to treat gout?

Accepted Answer

Allopurinol

Question 15

Which of the following best describes the difference between purine and pyrimidine biosynthesis?

Accepted Answer

Purine rings are built on a ribose-phosphate scaffold, while pyrimidine rings are synthesized before attachment to ribose-phosphate.

Question 16

Which enzyme catalyzes the committed and rate-limiting step in fatty acid synthesis?

Accepted Answer

Acetyl-CoA carboxylase

Question 17

A deficiency in adenosine deaminase (ADA) leads to which immunological disorder?

Accepted Answer

Severe combined immunodeficiency (SCID)

Question 18

Which of the following is a key regulatory effect of leptin on fat metabolism?

Accepted Answer

It inhibits fatty acid synthase expression in fat cells.

Question 19

Which of the following is a direct precursor for the synthesis of ketone bodies in the liver?

Accepted Answer

Acetyl-CoA

Question 20

Which of the following statements about eicosanoids is TRUE?

Accepted Answer

They are derived from 20-carbon fatty acids such as arachidonic acid.

Biochemistry of Lipid and Nucleotide Metabolism

Study Guide - Practice Questions