Deck 23: The Metabolism of Fatty Acids and Triglycerides

Question 1

The stimulation of fatty acid biosynthesis in the liver is achieved by:

A)Dephosphorylation of inactive acetyl-coenzyme A (CoA) carboxylase.
B)Phosphorylation of inactive fatty acid synthase.
C)Phosphorylation of inactive acetyl-CoA carboxylase.
D)Dephosphorylation of inactive fatty acid synthase.
E)High levels of the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH).

Answer 1

Dephosphorylation of inactive acetyl-coenzyme A (CoA) carboxylase.

Question 2

A patient complains about frequent aches and pains in his muscles.A blood test shows increased levels of creatine kinase MM, fatty acids and also myoglobin.A second blood sample, this time taken after an overnight fast, revealed low levels of blood glucose and elevated VLDL.This patient most likely has which of the following conditions?

A)Carnitine-acyl transferase deficiency.
B)Essential amino acid deficiency.
C)Type 1 glycogen storage disease.
D)Acute alcohol toxicity.
E)Elevated insulin levels, which cause hypoglycemia and increased fatty acid mobilization from adipose tissue.

Answer 2

Carnitine-acyl transferase deficiency.

Question 3

Ketone bodies can be used as a source of metabolic energy by most tissues.One tissue that cannot oxidize ketone bodies is:

A)Brain.
B)Myocardium.
C)Skeletal muscle.
D)Liver.
E)Adipose tissue.

Answer 3

Liver.

Question 4

A deficiency of which of the following proteins is least likely to impair the utilization of adipose tissue triglyceride for ATP production in muscle tissue?

A)Acyl-carnitine translocase.
B)Carnitine-acyl transferase-1.
C)Medium-chain acyl-CoA dehydrogenase.
D)Acetyl-CoA carboxylase.
E)Cytochrome oxidase.

Question 5

A 23-year-old woman has just eaten a meal consisting mainly of carbohydrates.Which of the following best describes the activity of LPL and hormone-sensitive lipase (HSL) in adipose tissue of this individual?

A)Both LPL and HSL activity are decreased.
B)LPL activity is decreased; HSL activity is increased.
C)LPL activity is increased; HSL activity is decreased.
D)Both LPL and HSL activity are increased.

Question 6

After a carbohydrate meal you can expect to find a high activity of _____ and low plasma levels of _____.

A)Hepatic lipase; very-low-density lipoprotein (VLDL).
B)Skeletal muscle lipoprotein lipase (LPL); chylomicrons.
C)Adipose tissue LPL; fatty acids.
D)Hormone-sensitive lipase; fatty acids.
E)Acetyl-CoA carboxylase; VLDL.

Question 7

A student who lives on only soft drinks and chocolate bars will have very little ẞ-oxidation of fatty acids in his liver.Why?

A)Phosphofructokinase-1 is inhibited by high glucose-6-phosphate levels.
B)Acetyl-CoA carboxylase is inhibited by high citrate levels.
C)Carnitine-acyl transferase-1 is inhibited by high malonyl-CoA levels.
D)Hepatic lipase is inhibited by high glucagon levels.
E)Pyruvate dehydrogenase activity is inhibited by high citrate levels.

Question 8

Epinephrine acts by phosphorylating and activating hormone-sensitive lipase in a matter of minutes.One hormone that can facilitate lipolysis in the long term by stimulating the synthesis of the enzyme is:

A)Adrenocorticotropin (ACTH).
B)Cortisol.
C)Glucagon.
D)Thyroid-stimulating hormone (TSH).
E)Insulin.

Question 9

In adipocytes, protein kinase A activates lipolysis by phosphorylating two proteins.These proteins are:

A)Lecithin-cholesterol acyl transferase (LCAT) and leptin.
B)Gs proteins and protein kinase C.
C)Signal transducer and activator of transcription (STAT) proteins and phospholipase A2.
D)Hormone-sensitive adipose tissue lipase and perilipin.
E)Protein kinase C and triglyceride transfer protein.

Question 10

A patient presents with low blood levels of glucose and ketones in plasma during fasting, accompanied by a high level of plasma free fatty acids.A urine analysis reveals high levels of dicarboxylic acids.The patient is most likely to benefit from:

A)A high-fat diet.
B)A low-fat, high-carbohydrate diet.
C)Low dietary carnitine.
D)A diet rich in essential fatty acids.
E)A high fat, high carbohydrate diet.

Question 11

A patient presents with low blood levels of glucose and ketones in plasma accompanied by high fatty acid levels.A urine analysis reveals high levels of dicarboxylic acids.This patient will most likely benefit from:

A)A high-fat, "ketogenic" diet.
B)A low-fat, high-carbohydrate diet.
C)High doses of carnitine.
D)A diet rich in essential fatty acids.
E)Restriction of dietary glycine.

Question 12

The oxidation of fatty acids in the liver during fasting produces large amounts of acetyl-CoA, the reduced form of nicotinamide adenine dinucleotide (NADH), and ATP.All of these products affect carbohydrate metabolism by:

A)Inhibition of lactate dehydrogenase.
B)Stimulation of lactate dehydrogenase.
C)Stimulation of pyruvate kinase.
D)Stimulation of phosphofructokinase.
E)Inhibition of pyruvate dehydrogenase.