Fatty Acid Synthesis
Which enzyme catalyzes the rate-limiting step of fatty acid synthesis?
Acetyl-CoA carboxylase
Which enzyme controls entry of long-chain fatty acids into the mitochondrial matrix?
CPT-I
Which enzyme is the rate-limiting enzyme of cholesterol synthesis?
HMG-CoA reductase (cytosolic)
Which enzyme is the rate-limiting step of ketone body synthesis?
HMG-CoA synthase (mitochondrial)
Which enzyme catalyzes the first step of the urea cycle?
CPS- I
(N-acetylglutamate is a required allosteric activator)
What molecule is produced by acetyl-CoA carboxylase?
Malonyl-CoA
A child develops hypoketotic hypoglycemia after prolonged fasting. Which disorder is
most likely?
MCAD deficiency
Which drug class directly inhibits HMG-CoA reductase?
Statins
Which organ primarily produces ketone bodies during prolonged fasting?
Liver
A male infant develops hyperammonemia and increased orotic acid. Which enzyme is deficient?
OTC
What is the major importance of malonyl-CoA?
inhibits CPT-I, preventing simultaneous fatty acid synthesis and oxidation
Why is β-oxidation impaired during severe carnitine deficiency?
Long-chain fatty acids cannot efficiently enter the mitochondrial matrix
HMG-CoA reductase converts HMG-CoA into which product?
Mevalonate
In uncontrolled type 1 diabetes, ↓ insulin causes ↑ lipolysis → ↑ fatty acids → ↑ β-oxidation. What molecule accumulates in the liver and is then used to make ketone bodies?
Acetyl-CoA
Where does the urea cycle occur?
First two steps in mitochondria, remaining steps in cytosol