Biochemistry Lipids and Membranes 2

Question 1

Beta-oxidation of fatty acids occurs primarily in which cellular compartment?

Accepted Answer

Mitochondrial matrix

Answer

Beta-oxidation of most fatty acids occurs in the mitochondrial matrix, where fatty acyl-CoA undergoes sequential rounds of oxidation to produce acetyl-CoA, NADH, and FADH₂.

Question 2

Carnitine plays an essential role in fatty acid oxidation by:

Accepted Answer

Transporting long-chain fatty acyl groups across the inner mitochondrial membrane

Answer

Carnitine shuttles long-chain fatty acyl groups across the inner mitochondrial membrane as acylcarnitine, which is essential because the inner membrane is impermeable to acyl-CoA.

Question 3

During fatty acid synthesis, malonyl-CoA is formed from acetyl-CoA by which enzyme?

Accepted Answer

Acetyl-CoA carboxylase (ACC)

Answer

Acetyl-CoA carboxylase (ACC) catalyzes the ATP-dependent carboxylation of acetyl-CoA to malonyl-CoA, the committed step in fatty acid synthesis.

Question 4

Fatty acid synthesis occurs in which cellular compartment?

Accepted Answer

Cytosol

Answer

Fatty acid synthesis by fatty acid synthase (FAS) occurs in the cytosol, using NADPH as the reducing agent and malonyl-CoA as the two-carbon donor.

Question 5

Ketone bodies are produced in the liver primarily from excess:

Accepted Answer

Acetyl-CoA

Answer

When acetyl-CoA from fatty acid oxidation exceeds the capacity of the TCA cycle (e.g., during fasting), the liver converts excess acetyl-CoA into ketone bodies (acetoacetate, β-hydroxybutyrate, acetone).

Biochemistry Practice Test

Biochemistry Practice Test

Biochemistry Lipids and Membranes 2