Which statement best describes carnitine's role in fatty acid metabolism?

Which statement best describes carnitine's role in fatty acid metabolism?

• A. It detoxifies ammonia.
• B. It is a hormone regulating appetite.
• C. It is a mineral involved in bone formation.
• D. It functions as a cofactor for transformation of free long-chain fatty acids into acylcarnitines and transport into the mitochondria.

Answer: (D)

Carnitine’s main job is to enable long-chain fatty acids to get into the mitochondria for beta-oxidation. It does this by forming acylcarnitines: long-chain fatty acids are transferred to carnitine by carnitine palmitoyltransferase I on the outer mitochondrial membrane, creating acylcarnitine. This carrier is then shuttled across the inner membrane by a specific transporter, and in the matrix, carnitine palmitoyltransferase II converts it back to acyl-CoA so the fatty acid can undergo beta-oxidation. This shuttle mechanism is why carnitine is described as a cofactor/substrate that transforms free long-chain fatty acids into acylcarnitines for mitochondrial entry and oxidation. It isn’t involved in ammonia detoxification, hormonal appetite regulation, or bone mineral processes.

Carnitine’s main job is to enable long-chain fatty acids to get into the mitochondria for beta-oxidation. It does this by forming acylcarnitines: long-chain fatty acids are transferred to carnitine by carnitine palmitoyltransferase I on the outer mitochondrial membrane, creating acylcarnitine. This carrier is then shuttled across the inner membrane by a specific transporter, and in the matrix, carnitine palmitoyltransferase II converts it back to acyl-CoA so the fatty acid can undergo beta-oxidation. This shuttle mechanism is why carnitine is described as a cofactor/substrate that transforms free long-chain fatty acids into acylcarnitines for mitochondrial entry and oxidation. It isn’t involved in ammonia detoxification, hormonal appetite regulation, or bone mineral processes.