Chapter 17

Question 1

Lipoprotein lipase acts in:

A) hydrolysis of triacylglycerols of plasma lipoproteins to supply fatty acids to various tissues.
B) intestinal uptake of dietary fat.
C) intracellular lipid breakdown of lipoproteins.
D) lipoprotein breakdown to supply needed amino acids.
E) none of the above.

Answer 1

A) hydrolysis of triacylglycerols of plasma lipoproteins to supply fatty acids to various tissues.

Question 2

Free fatty acids in the bloodstream are:

A) bound to hemoglobin.
B) carried by the protein serum albumin.
C) freely soluble in the aqueous phase of the blood.
D) nonexistent; the blood does not contain free fatty acids.
E) present at levels that are independent of epinephrine.

Answer 2

B) carried by the protein serum albumin.

Question 3

The role of hormone-sensitive triacylglycerol lipase is to:

A) hydrolyze lipids stored in the liver.
B) hydrolyze membrane phospholipids in hormone-producing cells.
C) hydrolyze triacylglycerols stored in adipose tissue.
D) synthesize lipids in adipose tissue.
E) synthesize triacylglycerols in the liver.

Answer 3

C) hydrolyze triacylglycerols stored in adipose tissue.

Question 4

Transport of fatty acids from the cytoplasm to the mitochondrial matrix requires:

A) ATP, carnitine, and coenzyme A.
B) ATP, carnitine, and pyruvate dehydrogenase.
C) ATP, coenzyme A, and hexokinase.
D) ATP, coenzyme A, and pyruvate dehydrogenase.
E) carnitine, coenzyme A, and hexokinase.

Answer 4

A) ATP, carnitine, and coenzyme A.

Question 5

Fatty acids are activated to acyl-CoAs and the acyl group is further transferred to carnitine because:

A) acyl-carnitines readily cross the mitochondrial inner membrane, but acyl-CoAs do not.
B) acyl-CoAs easily cross the mitochondrial membrane, but the fatty acids themselves will not.
C) carnitine is required to oxidize NAD+
to NADH.
D) fatty acids cannot be oxidized by FAD unless they are in the acyl-carnitine form.
E) None of the above is true.

Answer 5

A) acyl-carnitines readily cross the mitochondrial inner membrane, but acyl-CoAs do not.

Question 6

Carnitine is:

A) a 15-carbon fatty acid.
B) an essential cofactor for the citric acid cycle.
C) essential for intracellular transport of fatty acids.
D) one of the amino acids commonly found in protein.
E) present only in carnivorous animals.

Answer 6

C) essential for intracellular transport of fatty acids.

Question 7

Which of these is able to cross the inner mitochondrial membrane?

A) Acetyl–CoA
B) Fatty acyl–carnitine
C) Fatty acyl–CoA
D) Malonyl–CoA
E) None of the above can cross.

Answer 7

B) Fatty acyl–carnitine

Question 8

What is the correct order of function of the following enzymes of β oxidation?

1. β-Hydroxyacyl-CoA dehydrogenase
2. Thiolase
3. Enoyl-CoA hydratase
4. Acyl-CoA dehydrogenase

A) 1, 2, 3, 4
B) 3, 1, 4, 2
C) 4, 3, 1, 2
D) 1, 4, 3, 2
E) 4, 2, 3, 1

Answer 8

C) 4, 3, 1, 2

Question 9

If the 16-carbon saturated fatty acid palmitate is oxidized completely to carbon dioxide and water (via the β-oxidation pathway and the citric acid cycle), and all of the energy-conserving products are used
to drive ATP synthesis in the mitochondrion, the net yield of ATP per molecule of palmitate is:

A) 3.
B) 10.
C) 25.
D) 108.
E) 1,000

Answer 9

D) 108.

Question 10

Saturated fatty acids are degraded by the stepwise reactions of β oxidation, producing acetyl-CoA.
Under aerobic conditions, how many ATP molecules would be produced as a consequence of removal
of each acetyl-CoA?

A) 2
B) 3
C) 4
D) 5
E) 6

Answer 10

C) 4

Question 11

Which of the following is (are) true of the oxidation of 1 mol of palmitate (a 16-carbon saturated fatty
acid; 16:0) by the β-oxidation pathway, beginning with the free fatty acid in the cytoplasm?

1. Activation of the free fatty acid requires the equivalent of two ATPs.
2. Inorganic pyrophosphate (PPi) is produced.
3. Carnitine functions as an electron acceptor.
4. 8 mol of FADH2
   are formed.
5. 8 mol of acetyl-CoA are formed.
6. There is no direct involvement of NAD+
   .
   A) 1 and 5 only
   B) 1, 2, and 5
   C) 1, 2, and 6
   D) 1, 3, and 5
   E) 5 only

Answer 11

B) 1, 2, and 5

Question 12

Which of the following statements apply (applies) to the β oxidation of fatty acids?

1. The process takes place in the cytosol of mammalian cells.
2. Carbon atoms are removed from the acyl chain one at a time.
3. Before oxidation, fatty acids must be converted to their CoA derivatives.
4. NADP+
   is the electron acceptor.
5. The products of β oxidation can directly enter the citric acid cycle for further oxidation.

A) 1 and 3 only
B) 1, 2, and 3
C) 1, 2, and 5
D) 3 and 5 only
E) 4 only

Answer 12

D) 3 and 5 only

Question 13

Which of the following statements concerning the β oxidation of fatty acids is true?

A) About 1,200 ATP molecules are ultimately produced per 20-carbon fatty acid oxidized.
B) One FADH2 and two NADH are produced for each acetyl-CoA.
C) The free fatty acid must be carboxylated in the β position by a biotin-dependent reaction before
the process of β oxidation commences.
D) The free fatty acid must be converted to a thioester before the process of β oxidation
commences.
E) Two NADH are produced for each acetyl-CoA.

Answer 13

D) The free fatty acid must be converted to a thioester before the process of β oxidation
commences.

Question 14

The balanced equation for the degradation of CH3(CH2)10COOH via the β-oxidation pathway is:

A) [CH3(CH2)10COOH] + [5FAD] + [5NAD+] + [6CoA—SH] + [5H2O] + [ATP] → [6 Acetyl-CoA] + [5FADH2] + [5NADH] + [5H+] + [AMP] + [PPi]
B) [CH3(CH2)10COOH] + [5FAD] + [5NAD+] + [6CoA—SH] + [5H2O] → [6 Acetyl-CoA] + [5FADH2] + [5NADH] + [5H+]
C) [CH3(CH2)10COOH] + [6FAD] + [6NAD+] + [6CoA—SH] + [6H2O] + [ATP] → [6 Acetyl-CoA] + [6FADH2] + [6NADH] + [6H+] + AMP + PPi
D) [CH3(CH2)10COOH] + [6FAD] + [6NAD+] + [6CoA—SH] + [6H2O] → [6 Acetyl-CoA] + [6FADH2] + [6NADH] + [6H]

Answer 14

A) [CH3(CH2)10COOH] + [5FAD] + [5NAD+] + [6CoA—SH] + [5H2O] + [ATP] → [6 Acetyl-CoA] + [5FADH2] + [5NADH] + [5H+] + [AMP] + [PPi]

Question 15

Which compound is an intermediate of the β oxidation of fatty acids?

A) CH3—(CH2)20—CO—COOH
B) CH3—CH2—CO—CH2—CO—OPO3
2–
C) CH3—CH2—CO—CH2—OH
D) CH3—CH2—CO—CO—S—CoA
E) CH3—CO—CH2—CO—S—CoA

Answer 15

E) CH3—CO—CH2—CO—S—CoA

Question 16

The conversion of palmitoyl-CoA (16:0) to myristoyl-CoA (14:0) and 1 mol of acetyl-CoA by the βoxidation pathway results in the net formation of:

A) 1 FADH2 and 1 NADH.
B) 1 FADH2 and 1 NADPH.
C) 1 FADH2, 1 NADH, and 1 ATP.
D) 2 FADH2 and 2 NADH.
E) 2 FADH2, 2 NADH, and 1 ATP.

Answer 16

A) 1 FADH2 and 1 NADH.

Question 17

Which of the following is not true regarding the oxidation of 1 mol of palmitate (16:0) by the βoxidation pathway?

A) 1 mol of ATP is needed.
B) 8 mol of acetyl-CoA are formed.
C) 8 mol of FADH2
are formed.
D) AMP and PPi are formed.
E) The reactions occur in the mitochondria.

Answer 17

C) 8 mol of FADH2 are formed.

Question 18

If an aerobic organism (e.g., the bacterium E. coli) were fed each of the following four compounds as
a source of energy, the energy yield per mole from these molecules would be in the order:

A) alanine > glucose > palmitate (16:0)
B) glucose > alanine > palmitate
C) glucose > palmitate > alanine
D) palmitate > alanine > glucose
E) palmitate > glucose > alanine

Answer 18

E) palmitate > glucose > alanine

Question 19

Which of the following is (are) true of the β oxidation of long-chain fatty acids?

1. The enzyme complex that catalyzes the reaction contains biotin.
2. FADH2
   serves as an electron carrier.
3. NADH serves as an electron carrier.
4. Oxidation of an 18-carbon fatty acid produces six molecules of propionyl-CoA.
5. Oxidation of a 15-carbon fatty acid produces at least one propionyl-CoA.

A) 1, 2, and 3
B) 1, 2, and 5
C) 2, 3, and 4
D) 2, 3, and 5
E) 3 and 5 only

Answer 19

D) 2, 3, and 5

Question 20

The following fatty acid, in which the indicated carbon is labeled with 14C, is fed to an animal:

[14] CH3 (CH2)9 COOH
After allowing 30 minutes for fatty acid β oxidation, the label would most likely be recovered in:

A) acetyl-CoA.
B) beta-hydroxy butyryl-CoA.
C) both acetyl-CoA and propionyl-CoA.
D) palmitoyl-CoA.
E) propionyl-CoA.

Answer 20

E) propionyl-CoA.

Question 21

The carbon atoms from a fatty acid with an odd number of carbons will enter the citric acid cycle as
acetyl-CoA and:

A) butyrate.
B) citrate.
C) malate.
D) succinyl-CoA.
E) α-ketoglutarate.

Answer 21

D) succinyl-CoA.

Question 22

In the disease sprue, vitamin B12 (cobalamin) is poorly absorbed in the intestine, resulting in B12
deficiency. If each of the following fatty acids were in the diet, for which one would the process of
fatty acid oxidation be most affected in a patient with sprue?

A) CH3 (CH2)10 COOH
B) CH3 (CH2)11COOH
C) CH3 (CH2)12 COOH
D) CH3 (CH2)14 COOH
E) CH3 (CH2)18 COOH

Answer 22

B) CH3 (CH2)11COOH

Question 23

During β oxidation of fatty acids, ___________ is produced in peroxisomes but not in mitochondria.

A) acetyl-CoA
B) FADH2
C) H2O
D) H2O2
E) NADH

Answer 23

D) H2O2

Question 24

When comparing the β-oxidation and ω-oxidation pathways, which one of the following statements is
correct?

A) β-oxidation and ω-oxidation occur in the cytoplasm.
B) β oxidation occurs at the carboxyl end of the fatty acid whereas ω oxidation occurs at the methyl
end.
C) β oxidation occurs at the methyl end of the fatty acid whereas ω oxidation occurs at the carboxyl
end.
D) β oxidation occurs mainly in the cytoplasm whereas ω oxidation occurs mainly in the
mitochondria.
E) β oxidation occurs mainly in the mitochondria whereas ω oxidation occurs mainly in the
cytoplasm.

Answer 24

B) β oxidation occurs at the carboxyl end of the fatty acid whereas ω oxidation occurs at the methyl
end.

Question 25

Ketone bodies are formed in the liver and transported to the extrahepatic tissues mainly as:

A) acetoacetyl-CoA.
B) acetone.
C) beta-hydroxybutyric acid.
D) beta-hydroxybutyryl-CoA.
E) lactic acid

Answer 25

C) beta-hydroxybutyric acid.

Question 26

The major site of formation of acetoacetate from fatty acids is the:

A) adipose tissue.
B) intestinal mucosa.
C) kidney.
D) liver.
E) muscle.

Answer 26

D) liver.