BCH 361 EXAM TEST BANK
QUESTIONS WITH CORRECT
ANSWERS
Before degradation, fatty acids must be activated and transported into the matrix: -
Answer-a. FA is first adenylated. An ATP is expended to adenylate the FA. The AMP is
then replaced by CoA to form acyl CoA. The reaction is catalyzed by acyl CoA
synthetase.
b. Acyl CoA is then converted to acyl carnitine by replacing the CoA with carnitine. This
reaction is catalyzed by the enzyme carnitine acyltransferase I.
c. Acyl carnitine is then transported across the inner mitochondrial membrane by an
antiporter that also transports carnitine out of the matrix at the same time.
d. Acyl carnitine in the matrix is converted back to acyl CoA by carnitine acyltransferase
II.
the basic pathway used to degrade fatty acids into acetyl CoA - Answer-β-Oxidation
steps of β-Oxidation - Answer-a. Acyl CoA dehydrogenase creates a trans double bond
between carbons 2-3 (α-β, Δ2). The electrons freed by the reaction are used to reduce
FAD into FADH2.
b. A water molecule is added to the trans double bond to create L-3-hydroxyacyl CoA.
The reaction is catalyzed by enoyl CoA hydratase.
c. The hydroxyl group on carbon 3 (β) is oxidized into a ketone by the enzyme L-3-
hydroxyacyl CoA dehydrogenase. The freed electrons are transferred to NAD+ to
produce NADH.
d. The 3-ketoacyl CoA is then cleaved by thiolase to generate an acetyl CoA and an
acyl CoA shortened by two carbons. The cycle is repeated until the acyl chain is
completely converted to acetyl CoA.
to degrade cis-Δ3-enoyl CoA - Answer-a. cis- Δ3-enoyl CoA isomerase will convert
trans-Δ2-enoyl CoA.
b. This can then undergo β-oxidation.
to degrade cis-Δ4-enoyl CoA - Answer-a. Acyl CoA dehydrogenase will add a trans
double bond forming 2,4-dienoyl CoA.
b. 2,4-dienoyl CoA reductase will use electrons from NADPH to reduce the compound
to form trans- Δ3-enoyl CoA.
c. cis- Δ3-enoyl CoA isomerase will then convert trans- Δ3-enoyl CoA to trans-Δ2-enoyl
CoA.
d. This can then undergo β-oxidation.
, to degrade FAs containing cis- Δ3,6-dienoyl CoA - Answer-a. cis- Δ3-enoyl CoA
isomerase will convert the cis-Δ3 bond to trans Δ2.
b. One round of β-oxidation will remove the first two carbons and produce cis Δ4-enoyl
CoA.
c. The FA can then be degraded as in slide 6
to degrade FAs containing cis- Δ4, -dienoyl CoA - Answer-a. Use #5 to convert cis-Δ4 to
trans-Δ2.
b. Perform two rounds of β-oxidation.
c. The resulting product cis-Δ3-enoyl CoA can then be processed as in slide 5
to degrade the final three-carbon fragment from odd-chain fatty acid (propionyl CoA), -
Answer-Propionyl CoA carboxylase will first carboxylate it to produce a four carbon
fragment, methylmalonyl CoA. Methylmalonyl CoA is then converted to succinyl CoA,
which can be incorporated into the TCA cycle.
ketone bodies are synthesized in the liver from acetyl CoA generated from FA
degradation. They are synthesized in the following steps: - Answer-a. Acetyl CoAs are
first combined to form acetoacetate.
b. Aceoacetate is then reduced by NADH to form 3-hydroxybutyrate. It can also
spontaneously decarboxylate to form acetone.
c. 3-hydroxybutyrate is transported to other tissues and converted back to acetyl CoA.
The process is essentially a reversal of the ketone body synthetic pathway. Specifically,
3-hydroxybutyrate is oxidized back to acetoacetate. The acetoacetate is then attached
to CoA by CoA transferase. Finally, thiolase will convert acetoacetate CoA to acetyl
CoA.
Regulation of fatty acid degradation - Answer-mainly through the regulation of the
release of free fatty acids from adipose tissue.
The hormones glucagon and epinephrine activate PKA in adipocytes. This leads to the
activation of lipases that frees fatty acids from triacylglycerol (TAG). The fatty acids are
then transported to other cells for metabolism.
Synthesis of FA takes place in the__________ and is done by the mega enzyme
____________, which can only make palmitate (16:0). - Answer-cytoplasm; fatty acid
synthase
FA synthesis uses ________ as the basic building block and _________ as the
reducing agent. - Answer-acetyl CoA; NADPH
Because acetyl CoA is produced in the mitochondrial matrix, it is transported into the
cytoplasm by combining it with _________ to form _________. Citrate is then
transported into the _________ , where it is converted back to _________ and
_________ . To transport oxaloacetate back into the matrix, _________ is reduced to
_________ by _________ . Malate is then converted to pyruvate by _________. The
reaction also reduces NADP+ to NADPH, which will be used in FA synthesis. The
QUESTIONS WITH CORRECT
ANSWERS
Before degradation, fatty acids must be activated and transported into the matrix: -
Answer-a. FA is first adenylated. An ATP is expended to adenylate the FA. The AMP is
then replaced by CoA to form acyl CoA. The reaction is catalyzed by acyl CoA
synthetase.
b. Acyl CoA is then converted to acyl carnitine by replacing the CoA with carnitine. This
reaction is catalyzed by the enzyme carnitine acyltransferase I.
c. Acyl carnitine is then transported across the inner mitochondrial membrane by an
antiporter that also transports carnitine out of the matrix at the same time.
d. Acyl carnitine in the matrix is converted back to acyl CoA by carnitine acyltransferase
II.
the basic pathway used to degrade fatty acids into acetyl CoA - Answer-β-Oxidation
steps of β-Oxidation - Answer-a. Acyl CoA dehydrogenase creates a trans double bond
between carbons 2-3 (α-β, Δ2). The electrons freed by the reaction are used to reduce
FAD into FADH2.
b. A water molecule is added to the trans double bond to create L-3-hydroxyacyl CoA.
The reaction is catalyzed by enoyl CoA hydratase.
c. The hydroxyl group on carbon 3 (β) is oxidized into a ketone by the enzyme L-3-
hydroxyacyl CoA dehydrogenase. The freed electrons are transferred to NAD+ to
produce NADH.
d. The 3-ketoacyl CoA is then cleaved by thiolase to generate an acetyl CoA and an
acyl CoA shortened by two carbons. The cycle is repeated until the acyl chain is
completely converted to acetyl CoA.
to degrade cis-Δ3-enoyl CoA - Answer-a. cis- Δ3-enoyl CoA isomerase will convert
trans-Δ2-enoyl CoA.
b. This can then undergo β-oxidation.
to degrade cis-Δ4-enoyl CoA - Answer-a. Acyl CoA dehydrogenase will add a trans
double bond forming 2,4-dienoyl CoA.
b. 2,4-dienoyl CoA reductase will use electrons from NADPH to reduce the compound
to form trans- Δ3-enoyl CoA.
c. cis- Δ3-enoyl CoA isomerase will then convert trans- Δ3-enoyl CoA to trans-Δ2-enoyl
CoA.
d. This can then undergo β-oxidation.
, to degrade FAs containing cis- Δ3,6-dienoyl CoA - Answer-a. cis- Δ3-enoyl CoA
isomerase will convert the cis-Δ3 bond to trans Δ2.
b. One round of β-oxidation will remove the first two carbons and produce cis Δ4-enoyl
CoA.
c. The FA can then be degraded as in slide 6
to degrade FAs containing cis- Δ4, -dienoyl CoA - Answer-a. Use #5 to convert cis-Δ4 to
trans-Δ2.
b. Perform two rounds of β-oxidation.
c. The resulting product cis-Δ3-enoyl CoA can then be processed as in slide 5
to degrade the final three-carbon fragment from odd-chain fatty acid (propionyl CoA), -
Answer-Propionyl CoA carboxylase will first carboxylate it to produce a four carbon
fragment, methylmalonyl CoA. Methylmalonyl CoA is then converted to succinyl CoA,
which can be incorporated into the TCA cycle.
ketone bodies are synthesized in the liver from acetyl CoA generated from FA
degradation. They are synthesized in the following steps: - Answer-a. Acetyl CoAs are
first combined to form acetoacetate.
b. Aceoacetate is then reduced by NADH to form 3-hydroxybutyrate. It can also
spontaneously decarboxylate to form acetone.
c. 3-hydroxybutyrate is transported to other tissues and converted back to acetyl CoA.
The process is essentially a reversal of the ketone body synthetic pathway. Specifically,
3-hydroxybutyrate is oxidized back to acetoacetate. The acetoacetate is then attached
to CoA by CoA transferase. Finally, thiolase will convert acetoacetate CoA to acetyl
CoA.
Regulation of fatty acid degradation - Answer-mainly through the regulation of the
release of free fatty acids from adipose tissue.
The hormones glucagon and epinephrine activate PKA in adipocytes. This leads to the
activation of lipases that frees fatty acids from triacylglycerol (TAG). The fatty acids are
then transported to other cells for metabolism.
Synthesis of FA takes place in the__________ and is done by the mega enzyme
____________, which can only make palmitate (16:0). - Answer-cytoplasm; fatty acid
synthase
FA synthesis uses ________ as the basic building block and _________ as the
reducing agent. - Answer-acetyl CoA; NADPH
Because acetyl CoA is produced in the mitochondrial matrix, it is transported into the
cytoplasm by combining it with _________ to form _________. Citrate is then
transported into the _________ , where it is converted back to _________ and
_________ . To transport oxaloacetate back into the matrix, _________ is reduced to
_________ by _________ . Malate is then converted to pyruvate by _________. The
reaction also reduces NADP+ to NADPH, which will be used in FA synthesis. The
