Lipid metabolism: carnitine shuttle: practice question

A Biochemistry question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Biochemistry · Lipid metabolism: carnitine shuttle

Sample item

What is the main role of carnitine in fatty-acid metabolism?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. Transport long-chain fatty acids into mitochondria

Long-chain fatty acyl groups require the carnitine shuttle to cross the inner mitochondrial membrane for beta oxidation. Medium- and short-chain fatty acids do not require this transport system.

Option by option

  • A. Synthesize ketone bodies in cytosol

    Ketone bodies are synthesized in liver mitochondria.

  • B. Convert cholesterol into bile salts directly

    Bile salt synthesis is a hepatic cholesterol pathway.

  • C. Transport long-chain fatty acids into mitochondria (correct)

    Correct. Carnitine moves long-chain acyl groups into the mitochondrial matrix.

  • D. Hydrolyze triglycerides in adipose tissue

    Hormone-sensitive lipase mobilizes adipose triglyceride.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is C, Transport long-chain fatty acids into mitochondria. Long-chain fatty acyl groups require the carnitine shuttle to cross the inner mitochondrial membrane for beta oxidation.

Why is "Synthesize ketone bodies in cytosol" not the answer?

Ketone bodies are synthesized in liver mitochondria.

Why is "Convert cholesterol into bile salts directly" not the answer?

Bile salt synthesis is a hepatic cholesterol pathway.

Why is "Hydrolyze triglycerides in adipose tissue" not the answer?

Hormone-sensitive lipase mobilizes adipose triglyceride.

What concept does this question test?

It tests Lipid metabolism: carnitine shuttle in Biochemistry. Medium- and short-chain fatty acids do not require this transport system.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Lipid metabolism: carnitine shuttle?

Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Then use the flashcards and the other Biochemistry questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.