Unit 3 Exam
Question 1
NADPH is essential for fatty acid synthesis and can be generated by which two enzymes? (+
indicates NADPH can be produced by the enzyme; - indicates the enzyme does not produce
NAPDH)
Glucose 6-phosphate Malic enzyme Pyruvate dehydrogenase complex
dehydrogenase
1 + + -
2 + - -
3 - - -
4 - + +
2
1
4
3
Selected
Answer:
2
Correct
Answer:
1
Response NAPDH is generated primarily by the pentose phosphate pathway by glucose
Feedback: oxidation by glucose 6-phosphate dehydrogenase or through malic enzyme
as it oxidized malate to pyruvate.
Question 2
An individual consumes a large meal consisting of a cheeseburger and fries. Which of the
following intermediates is shuttled out of the TCA cycle to be used as a substrate for fatty
acid synthesis?
Citrate
Isocitrate
Oxaloacetate
Malate
Selected
Answer:
Citrate
Correct Answer:
Citrate
Response The tricarboxylate transporter is responsible for moving citrate from the
Feedback:
, mitochondria to the cytosol for fatty acid synthesis.
Question 3
Which of the following is the regulatory enzyme for fatty acid synthesis?
Citrate lyase
Malic enzyme
Fatty acid synthase
Acetyl-CoA
carboxylase
Selected
Answer:
Acetyl-CoA
carboxylase
Correct Answer:
Acetyl-CoA
carboxylase
Response The regulatory step in fatty acid synthesis is the synthesis of malonyl-CoA by
Feedback: acetyl-CoA carboxylase. This reaction uses CO2 and biotin to add carbon to
cytosolic acetyl-CoA.
Question 4
A defect in the thioesterase subunit of fatty acid synthase would impair which of the
following activities of the enzyme complex?
Binding of malonyl-CoA to an SH group
Liberation of newly assembled palmitate from the
enzyme
Liberation of CO2 from 3-ketoacyl synthase
Priming of the enzyme with acetyl-CoA
Selected
Answer:
Liberation of newly assembled palmitate from the
enzyme
Correct Answer:
Liberation of newly assembled palmitate from the
enzyme
Response Fatty acid synthase is a multimeric enzyme and the final and sixth enzyme
Feedback: in the chain is the thioesterase which will liberate the newly formed
, palmitate.
Question 5
During fatty acid synthesis, after the initial step involving acetyl-CoA, the fatty acid chain is
elongated by the addition of which of the following compounds?
Acyl-CoA
Acetyl-
CoA
Succinyl-
CoA
Malonyl-
CoA
Selected
Answer:
Malonyl-
CoA
Correct
Answer:
Malonyl-
CoA
Response Initially, acetyl-CoA is bound to the acyl carrier protein (ACP),
Feedback: after this all subsequence 2 carbon units are added via malonyl-
CoA.
Question 6
Which of the following enzymes is correctly paired with its allosteric inhibitor?
Carnitine palmitoyl transferase I:
acetyl-CoA
Pyruvate dehydrogenase complex:
pyruvate
Acetyl-CoA carboxylase: palmitoyl-
CoA
Pyruvate kinase: fructose 1,6-
bisphosphate
Selected Answer:
Acetyl-CoA carboxylase: palmitoyl-CoA
Question 1
NADPH is essential for fatty acid synthesis and can be generated by which two enzymes? (+
indicates NADPH can be produced by the enzyme; - indicates the enzyme does not produce
NAPDH)
Glucose 6-phosphate Malic enzyme Pyruvate dehydrogenase complex
dehydrogenase
1 + + -
2 + - -
3 - - -
4 - + +
2
1
4
3
Selected
Answer:
2
Correct
Answer:
1
Response NAPDH is generated primarily by the pentose phosphate pathway by glucose
Feedback: oxidation by glucose 6-phosphate dehydrogenase or through malic enzyme
as it oxidized malate to pyruvate.
Question 2
An individual consumes a large meal consisting of a cheeseburger and fries. Which of the
following intermediates is shuttled out of the TCA cycle to be used as a substrate for fatty
acid synthesis?
Citrate
Isocitrate
Oxaloacetate
Malate
Selected
Answer:
Citrate
Correct Answer:
Citrate
Response The tricarboxylate transporter is responsible for moving citrate from the
Feedback:
, mitochondria to the cytosol for fatty acid synthesis.
Question 3
Which of the following is the regulatory enzyme for fatty acid synthesis?
Citrate lyase
Malic enzyme
Fatty acid synthase
Acetyl-CoA
carboxylase
Selected
Answer:
Acetyl-CoA
carboxylase
Correct Answer:
Acetyl-CoA
carboxylase
Response The regulatory step in fatty acid synthesis is the synthesis of malonyl-CoA by
Feedback: acetyl-CoA carboxylase. This reaction uses CO2 and biotin to add carbon to
cytosolic acetyl-CoA.
Question 4
A defect in the thioesterase subunit of fatty acid synthase would impair which of the
following activities of the enzyme complex?
Binding of malonyl-CoA to an SH group
Liberation of newly assembled palmitate from the
enzyme
Liberation of CO2 from 3-ketoacyl synthase
Priming of the enzyme with acetyl-CoA
Selected
Answer:
Liberation of newly assembled palmitate from the
enzyme
Correct Answer:
Liberation of newly assembled palmitate from the
enzyme
Response Fatty acid synthase is a multimeric enzyme and the final and sixth enzyme
Feedback: in the chain is the thioesterase which will liberate the newly formed
, palmitate.
Question 5
During fatty acid synthesis, after the initial step involving acetyl-CoA, the fatty acid chain is
elongated by the addition of which of the following compounds?
Acyl-CoA
Acetyl-
CoA
Succinyl-
CoA
Malonyl-
CoA
Selected
Answer:
Malonyl-
CoA
Correct
Answer:
Malonyl-
CoA
Response Initially, acetyl-CoA is bound to the acyl carrier protein (ACP),
Feedback: after this all subsequence 2 carbon units are added via malonyl-
CoA.
Question 6
Which of the following enzymes is correctly paired with its allosteric inhibitor?
Carnitine palmitoyl transferase I:
acetyl-CoA
Pyruvate dehydrogenase complex:
pyruvate
Acetyl-CoA carboxylase: palmitoyl-
CoA
Pyruvate kinase: fructose 1,6-
bisphosphate
Selected Answer:
Acetyl-CoA carboxylase: palmitoyl-CoA
