Lipid metabolism: re-esterification of dietary fat in enterocytes: 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.

Try it

Biochemistry · Lipid metabolism: re-esterification of dietary fat in enterocytes

Sample item

After absorption of monoacylglycerol and free fatty acids, enterocytes must rebuild triglycerides before they are packed into chylomicrons. Which pathway mainly carries out this resynthesis?

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

The answer and the reasoning

C. Acylation of 2-monoacylglycerol by acyltransferases

In the intestinal mucosa the monoacylglycerol pathway re-esterifies absorbed 2-monoacylglycerol with fatty acyl-CoA, using monoacylglycerol and diacylglycerol acyltransferases. Triglyceride then joins apoB-48 in the chylomicron. Intestinal cells have little glycerol kinase, so the glycerol-3-phosphate route is minor here.

Option by option

  • A. Conversion of phosphatidic acid to triglyceride in adipose tissue

    Adipose tissue makes triglyceride for storage, and this is not the site of chylomicron assembly.

  • B. De novo synthesis from acetyl-CoA in the cytosol

    De novo synthesis from acetyl-CoA makes fatty acids but does not rebuild triglyceride from absorbed lipolysis products.

  • C. Acylation of 2-monoacylglycerol by acyltransferases (correct)

    Correct. Absorbed 2-monoacylglycerol is directly acylated, so intestinal triglyceride resynthesis uses this pathway.

  • D. Acylation of glycerol-3-phosphate from glycerol kinase

    Glycerol-3-phosphate acylation is the main route in liver and adipose tissue and is minor in the intestine.

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.

More Biochemistry questions

Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is C, Acylation of 2-monoacylglycerol by acyltransferases. In the intestinal mucosa the monoacylglycerol pathway re-esterifies absorbed 2-monoacylglycerol with fatty acyl-CoA, using monoacylglycerol and diacylglycerol acyltransferases.

Why is "Conversion of phosphatidic acid to triglyceride in adipose tissue" not the answer?

Adipose tissue makes triglyceride for storage, and this is not the site of chylomicron assembly.

Why is "De novo synthesis from acetyl-CoA in the cytosol" not the answer?

De novo synthesis from acetyl-CoA makes fatty acids but does not rebuild triglyceride from absorbed lipolysis products.

Why is "Acylation of glycerol-3-phosphate from glycerol kinase" not the answer?

Glycerol-3-phosphate acylation is the main route in liver and adipose tissue and is minor in the intestine.

What concept does this question test?

It tests Lipid metabolism: re-esterification of dietary fat in enterocytes in Biochemistry. Triglyceride then joins apoB-48 in the chylomicron. Intestinal cells have little glycerol kinase, so the glycerol-3-phosphate route is minor here.

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: re-esterification of dietary fat in enterocytes?

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.