MCB 450 Exam 4 UPDATED QUESTIONS
AND CORRECT ANSWERS
Why do lipoproteins (e.g. VLDL) only have a monolayer of phospholipids instead of a typical lipid
bilayer?
A. The phosphate of the lipids interact with the triglycerides and cholesterol esters of the particle.
B. The monolayer protects the particles from bile acids
C. The acyl chains of the phospholipid monolayer interact with the triglycerides and cholesterol esters
of the particle.
D. The glycerol backbone solubilize the triglycerides
E. The monolayer blocks proteases from degrading the particles - CORRECT ANSWER C.
The acyl chains of the phospholipid monolayer interact with triglycerides and cholesterol esters of the
particle
Odd chain fatty acids and some amino acids produce propionyl CoA. Which of the following is NOT
required for the metabolism of propionyl CoA to succinyl CoA
A. NADH
B. Propionyl CoA carboxylase
C. Methylmalonyl CoA mutase
D. Vitamin B12
E. Biotin - CORRECT ANSWER NADH
Human can convert cholesterol to each of the following, except;
A. CO2 + H2O
B. Cortisol
C. Testosterone
D. Estradiol
E. Bile acids - CORRECT ANSWER CO2 and H20
,Mammalian pyruvate dehydrogenase component E1 is inactivated through phosphorylation in the
presence of _______?
A. High ADP
B. High pyruvate
C. Insulin
D. High Acetyl-CoA
E. High AMP - CORRECT ANSWER D. High Acetyl-CoA
Lovastatin is used to lower cholesterol by inhibiting the function of which protein?
A. HMG-CoA reductase
B. LDL receptor
C. Lipoprotein lipase
D. Cyclooxygenase
E. Alcohol dehydrogenase - CORRECT ANSWER A. HMG-CoA reductase
During vigorous exercise, stimulation of the tricarboxylic acid (TCA) cycle results principally from
_____?
A. Allosteric activation of a number of TCA cycle enzymes by increased levels of NADH
B. Allosteric activation of fumarase by increased cellular ADP concentrations
C. Stimulation of the flux through a number of TCA cycle enzymes by a decreased NADH/NAD+
ratio
D. A rapid decrease in the concentration of four carbon intermediates being used by other metabolic
pathways, e.g. gluconeogenesis
E. Product inhibition of the citrate synthase enzyme, which blocks the condensation of Acetyl CoA
and oxaloacetate - CORRECT ANSWER C. Stimulation of the flux through a number of TCA
cycle enzymes by a decreased NADH/NAD+ ratio
Triacylglycerol synthesis in adipose tissue occurs only in the fed state. Why?
A. Coenzyme A being required to activate the fatty acids prior to coupling to glycerol-3 phosphate
B. Lipoprotein lipase being activated only in the fed state by Apo-CII
C. Fatty acid for triacylglycerol synthesis being obtained from chylomicrons and VLDL, which is
high in concentration after a meal with high fat content
,D. Adipose tissue lacks glycerol kinase to make glycerol-3-phosphate from glycerol. Therefore,
Glycerol-3-phosphate can only be obtained from the glycolytic pathway (fed state), and the reduction
of dihydroxyacetone phosphate (DHAP)
E. None of the above. - CORRECT ANSWER D. Adipose tissue lacks glycerol kinase to make
glycerol-3-phosphate from glycerol. Therefore, Glycerol 3-phosphate can only be obtained from the
glycolytic pathway (fed state) and the reduction of DHAP
A patient with a genetic defect in lipoprotein lipase would be expected to exhibit which of the
following?
A. A deficiency in release of fatty acids from adipocytes during fasting
B. Elevated glucose in fasting blood samples
C. Elevated intestinal absorption of fats
D. Elevated chylomicrons in fasting blood samples
E. Decreasing recycling of bile salts - CORRECT ANSWER D. Elevated chylomicrons in
fasting blood samples
Suppose 14-C labeled CO2 is used to form malonyl CoA from acetyl CoA. if this labeled malonyl
CoA is used for palmitate synthesis, which carbons in the fatty acid would be radiolabeled?
A. The methyl terminal carbon
B. Only the alpha and beta-carbons
C. All odd numbered carbons
D. All even numbered carbons
E. None of the carbons - CORRECT ANSWER E. none of the carbons
Fatty acids are adenylated prior to reacting with Coenzyme A to make Acyl-CoA. What is the purpose
of the adenylation?
A. This creates a phospho-ester bond that can be "attacked" by Coenzyme A
B. Adenylation prevents Acyl-CoA from interacting with coenzyme A
C. Adenylation leads to the addition of ATP to the acyl chains
D. This allows for the growth of acyl chain length
, E. All of the above - CORRECT ANSWER A. this creates a phospho ester bond that can be
attacked by Coenzyme A
The carnitine derivatives of fatty acids are utilized for
A. Carrying fatty acids during fatty acid synthesis
B. Shuttling fatty acids across the mitochondrial membrane
C. One of the intermediates during beta-oxidation
D. Transporting fatty acids across the plasma membrane of the cell
E. Transporting fatty acids in plasma - CORRECT ANSWER B. Shuttling fatty acids across the
mitochondrial membrane
Which of the following compounds is a potent stimulator of palmitate synthesis, an allosteric activator
of acetyl-CoA carboxylase, and a source of both cytoplasmic acetyl-CoA and NADPH for
lipogenesis?
A. Biotin
B. Glucose 6-phosphate
C. Citrate
D. Pantothenic acid
E. L-carnitine - CORRECT ANSWER C. Citrate
Which of the following is responsible for down regulation of fatty acid synthesis under low energy
conditions?
A. Release of ATP inhibition of carnitine acyl transferase I
B. AMP activation of AMP activated protein kinase (AMPK)
C. AMP activation of PFK-1
D. AMP activation of PEP carboxykinase
E. Release of ATP inhibition of acetyl CoA carboxylase - CORRECT ANSWER B. AMP
activation of AMP activated protein kinase (AMPK)
AND CORRECT ANSWERS
Why do lipoproteins (e.g. VLDL) only have a monolayer of phospholipids instead of a typical lipid
bilayer?
A. The phosphate of the lipids interact with the triglycerides and cholesterol esters of the particle.
B. The monolayer protects the particles from bile acids
C. The acyl chains of the phospholipid monolayer interact with the triglycerides and cholesterol esters
of the particle.
D. The glycerol backbone solubilize the triglycerides
E. The monolayer blocks proteases from degrading the particles - CORRECT ANSWER C.
The acyl chains of the phospholipid monolayer interact with triglycerides and cholesterol esters of the
particle
Odd chain fatty acids and some amino acids produce propionyl CoA. Which of the following is NOT
required for the metabolism of propionyl CoA to succinyl CoA
A. NADH
B. Propionyl CoA carboxylase
C. Methylmalonyl CoA mutase
D. Vitamin B12
E. Biotin - CORRECT ANSWER NADH
Human can convert cholesterol to each of the following, except;
A. CO2 + H2O
B. Cortisol
C. Testosterone
D. Estradiol
E. Bile acids - CORRECT ANSWER CO2 and H20
,Mammalian pyruvate dehydrogenase component E1 is inactivated through phosphorylation in the
presence of _______?
A. High ADP
B. High pyruvate
C. Insulin
D. High Acetyl-CoA
E. High AMP - CORRECT ANSWER D. High Acetyl-CoA
Lovastatin is used to lower cholesterol by inhibiting the function of which protein?
A. HMG-CoA reductase
B. LDL receptor
C. Lipoprotein lipase
D. Cyclooxygenase
E. Alcohol dehydrogenase - CORRECT ANSWER A. HMG-CoA reductase
During vigorous exercise, stimulation of the tricarboxylic acid (TCA) cycle results principally from
_____?
A. Allosteric activation of a number of TCA cycle enzymes by increased levels of NADH
B. Allosteric activation of fumarase by increased cellular ADP concentrations
C. Stimulation of the flux through a number of TCA cycle enzymes by a decreased NADH/NAD+
ratio
D. A rapid decrease in the concentration of four carbon intermediates being used by other metabolic
pathways, e.g. gluconeogenesis
E. Product inhibition of the citrate synthase enzyme, which blocks the condensation of Acetyl CoA
and oxaloacetate - CORRECT ANSWER C. Stimulation of the flux through a number of TCA
cycle enzymes by a decreased NADH/NAD+ ratio
Triacylglycerol synthesis in adipose tissue occurs only in the fed state. Why?
A. Coenzyme A being required to activate the fatty acids prior to coupling to glycerol-3 phosphate
B. Lipoprotein lipase being activated only in the fed state by Apo-CII
C. Fatty acid for triacylglycerol synthesis being obtained from chylomicrons and VLDL, which is
high in concentration after a meal with high fat content
,D. Adipose tissue lacks glycerol kinase to make glycerol-3-phosphate from glycerol. Therefore,
Glycerol-3-phosphate can only be obtained from the glycolytic pathway (fed state), and the reduction
of dihydroxyacetone phosphate (DHAP)
E. None of the above. - CORRECT ANSWER D. Adipose tissue lacks glycerol kinase to make
glycerol-3-phosphate from glycerol. Therefore, Glycerol 3-phosphate can only be obtained from the
glycolytic pathway (fed state) and the reduction of DHAP
A patient with a genetic defect in lipoprotein lipase would be expected to exhibit which of the
following?
A. A deficiency in release of fatty acids from adipocytes during fasting
B. Elevated glucose in fasting blood samples
C. Elevated intestinal absorption of fats
D. Elevated chylomicrons in fasting blood samples
E. Decreasing recycling of bile salts - CORRECT ANSWER D. Elevated chylomicrons in
fasting blood samples
Suppose 14-C labeled CO2 is used to form malonyl CoA from acetyl CoA. if this labeled malonyl
CoA is used for palmitate synthesis, which carbons in the fatty acid would be radiolabeled?
A. The methyl terminal carbon
B. Only the alpha and beta-carbons
C. All odd numbered carbons
D. All even numbered carbons
E. None of the carbons - CORRECT ANSWER E. none of the carbons
Fatty acids are adenylated prior to reacting with Coenzyme A to make Acyl-CoA. What is the purpose
of the adenylation?
A. This creates a phospho-ester bond that can be "attacked" by Coenzyme A
B. Adenylation prevents Acyl-CoA from interacting with coenzyme A
C. Adenylation leads to the addition of ATP to the acyl chains
D. This allows for the growth of acyl chain length
, E. All of the above - CORRECT ANSWER A. this creates a phospho ester bond that can be
attacked by Coenzyme A
The carnitine derivatives of fatty acids are utilized for
A. Carrying fatty acids during fatty acid synthesis
B. Shuttling fatty acids across the mitochondrial membrane
C. One of the intermediates during beta-oxidation
D. Transporting fatty acids across the plasma membrane of the cell
E. Transporting fatty acids in plasma - CORRECT ANSWER B. Shuttling fatty acids across the
mitochondrial membrane
Which of the following compounds is a potent stimulator of palmitate synthesis, an allosteric activator
of acetyl-CoA carboxylase, and a source of both cytoplasmic acetyl-CoA and NADPH for
lipogenesis?
A. Biotin
B. Glucose 6-phosphate
C. Citrate
D. Pantothenic acid
E. L-carnitine - CORRECT ANSWER C. Citrate
Which of the following is responsible for down regulation of fatty acid synthesis under low energy
conditions?
A. Release of ATP inhibition of carnitine acyl transferase I
B. AMP activation of AMP activated protein kinase (AMPK)
C. AMP activation of PFK-1
D. AMP activation of PEP carboxykinase
E. Release of ATP inhibition of acetyl CoA carboxylase - CORRECT ANSWER B. AMP
activation of AMP activated protein kinase (AMPK)
