MCB 2000 Biochemistry Final Exam
and All Correct Answers 2025-2026
Updated.
What is cholesterol? - Answer It has three 6-membered rings and one 5-membered ring
fused together.
It contains a -OH functional group on one of the rings.
It provides the chemical backbone for vitamin D biosynthesis.
The liver is the major site for cholesterol biosynthesis.
List the steps involved in cholesterol biosynthesis. - Answer 1. Acetoacetyl CoA
2. HMG CoA
3. 3-isopentenyl pyrophosphate
4. Geranylpyrophosphate
5. Farnesyl pyrophosphate
6. Squalene
What is the rate-limiting enzyme in cholesterol biosynthesis? - Answer HMG CoA
The rate-limiting enzyme in cholesterol biosynthesis yields this product: - Answer
Mevalonate
What inhibits HMG CoA reductase? - Answer It is inhibited by phosphorylation in response
to AMP-activated protein kinase.
Activation of the gene for HMG CoA reductase _________ the amount of the protein. - Answer
increases
The cyclization and hydroxylation reactions in cholesterol biosynthesis require __________ and
___________. These reactions occur in the ________. - Answer oxygen; NADPH; smooth
endoplasmic reticulum
Mutation in the LDL receptor can result in: - Answer increase of cholesterol biosynthesis in
, Where does gluconeogenesis occur? - Answer In the liver along with glycogen degradation
What can provide a carbon skeleton for gluconeogenesis? - Answer Lactate
Alanine
Alpha-ketoglutarate
What is phosphoenolpyruvate carboxykinase (PEPCK)? - Answer A gluconeogenic enzyme
that opposes the pyruvate kinase step in glycolysis
What does PEPCK catalyze? - Answer The synthesis of a high energy bond
PEPCK is one of the energy _____________ steps in ________________. - Answer
consuming; gluconeogenesis
Fructose-1,6-biphosphatase and phosphofructokinase are inversely regulated by ____________
and _______________. - Answer fructose-2,6-biphosphate; AMP
What occurs during gluconeogenesis? - Answer High acetyl CoA, NADH, and ATP/ADP from
beta-oxidation inhibit pyruvate dehydrogenase and prevent conversion of pyruvate to acetyl
CoA.
Pyruvate kinase is inactivated by phosphorylation.
Pyruvate carboxylase is activated by high acetyl CoA.
ATP and GTP are consumed due to making of high energy bonds.
What would a mutation in glucose-6-phosphatase result in? - Answer Hypoglycemia and
inability to maintain glucose levels during overnight fast
What does glucose-6-phosphatase do? - Answer It hydrolyzes glucose-6-phosphate, creating
a phosphate group and free glucose.
What is the role of glycerol kinase? - Answer It is involved in triglyceride biosynthesis and
gluconeogenesis.
and All Correct Answers 2025-2026
Updated.
What is cholesterol? - Answer It has three 6-membered rings and one 5-membered ring
fused together.
It contains a -OH functional group on one of the rings.
It provides the chemical backbone for vitamin D biosynthesis.
The liver is the major site for cholesterol biosynthesis.
List the steps involved in cholesterol biosynthesis. - Answer 1. Acetoacetyl CoA
2. HMG CoA
3. 3-isopentenyl pyrophosphate
4. Geranylpyrophosphate
5. Farnesyl pyrophosphate
6. Squalene
What is the rate-limiting enzyme in cholesterol biosynthesis? - Answer HMG CoA
The rate-limiting enzyme in cholesterol biosynthesis yields this product: - Answer
Mevalonate
What inhibits HMG CoA reductase? - Answer It is inhibited by phosphorylation in response
to AMP-activated protein kinase.
Activation of the gene for HMG CoA reductase _________ the amount of the protein. - Answer
increases
The cyclization and hydroxylation reactions in cholesterol biosynthesis require __________ and
___________. These reactions occur in the ________. - Answer oxygen; NADPH; smooth
endoplasmic reticulum
Mutation in the LDL receptor can result in: - Answer increase of cholesterol biosynthesis in
, Where does gluconeogenesis occur? - Answer In the liver along with glycogen degradation
What can provide a carbon skeleton for gluconeogenesis? - Answer Lactate
Alanine
Alpha-ketoglutarate
What is phosphoenolpyruvate carboxykinase (PEPCK)? - Answer A gluconeogenic enzyme
that opposes the pyruvate kinase step in glycolysis
What does PEPCK catalyze? - Answer The synthesis of a high energy bond
PEPCK is one of the energy _____________ steps in ________________. - Answer
consuming; gluconeogenesis
Fructose-1,6-biphosphatase and phosphofructokinase are inversely regulated by ____________
and _______________. - Answer fructose-2,6-biphosphate; AMP
What occurs during gluconeogenesis? - Answer High acetyl CoA, NADH, and ATP/ADP from
beta-oxidation inhibit pyruvate dehydrogenase and prevent conversion of pyruvate to acetyl
CoA.
Pyruvate kinase is inactivated by phosphorylation.
Pyruvate carboxylase is activated by high acetyl CoA.
ATP and GTP are consumed due to making of high energy bonds.
What would a mutation in glucose-6-phosphatase result in? - Answer Hypoglycemia and
inability to maintain glucose levels during overnight fast
What does glucose-6-phosphatase do? - Answer It hydrolyzes glucose-6-phosphate, creating
a phosphate group and free glucose.
What is the role of glycerol kinase? - Answer It is involved in triglyceride biosynthesis and
gluconeogenesis.
