Question

Which of the following helps in the transport of fatty acids across the inner mitochondrial membrane?

• A. Acyl carrier protein
• B. Carnitine
• C. Lecithin-cholesterol acyltransferase
• D. Carnitine and albumin

Answer 1

The Correct Option is B

In biochemistry, the transport of fatty acids across the inner mitochondrial membrane is a crucial step in fatty acid oxidation. This process is facilitated by the compound carnitine. Carnitine acts as a carrier molecule that transports activated fatty acids from the cytosol into the mitochondrial matrix, where they undergo β-oxidation to produce energy in the form of ATP.

Here is the process by which carnitine functions:

• Activation of fatty acids: Before transportation, fatty acids are activated in the cytosol to form acyl-CoA by the enzyme acyl-CoA synthetase.
• Formation of acyl-carnitine: The acyl group from the acyl-CoA is transferred to carnitine by the enzyme carnitine acyltransferase I, located on the outer mitochondrial membrane. This forms acyl-carnitine.
• Transport across the membrane: The acyl-carnitine is then transported across the inner mitochondrial membrane by a translocase enzyme.
• Regeneration of acyl-CoA: Inside the mitochondrial matrix, another enzyme, carnitine acyltransferase II, transfers the acyl group back to CoA to form acyl-CoA, which enters β-oxidation, while free carnitine is recycled back to the cytosol.

Therefore, the correct answer to the question is carnitine, as it is the molecule responsible for transferring long-chain fatty acids into the mitochondria where they can be broken down for energy.