Vitamins and minerals: iron regulatory proteins: 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 · Vitamins and minerals: iron regulatory proteins

Sample item

A cell becomes iron deficient. Iron regulatory protein binds iron-responsive elements on messenger RNA. Which change in protein synthesis follows?

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

The answer and the reasoning

A. Ferritin translation falls and transferrin receptor mRNA is stabilised

In iron deficiency the regulatory protein binds the 5-prime element of ferritin mRNA, blocking translation, and the 3-prime elements of transferrin receptor mRNA, stabilising it. The cell therefore stores less iron and takes up more. With iron excess the opposite occurs.

Option by option

  • A. Ferritin translation falls and transferrin receptor mRNA is stabilised (correct)

    Correct. Less storage protein and more uptake receptor is the adaptive response to iron lack.

  • B. Both ferritin and transferrin receptor synthesis rise

    Ferritin translation is repressed, not increased, in iron deficiency.

  • C. Both ferritin and transferrin receptor synthesis fall

    Transferrin receptor mRNA is stabilised, not reduced, when iron is scarce.

  • D. Ferritin translation rises and transferrin receptor mRNA is degraded

    This is the pattern seen in iron-replete cells.

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 A, Ferritin translation falls and transferrin receptor mRNA is stabilised. In iron deficiency the regulatory protein binds the 5-prime element of ferritin mRNA, blocking translation, and the 3-prime elements of transferrin receptor mRNA, stabilising it.

Why is "Both ferritin and transferrin receptor synthesis rise" not the answer?

Ferritin translation is repressed, not increased, in iron deficiency.

Why is "Both ferritin and transferrin receptor synthesis fall" not the answer?

Transferrin receptor mRNA is stabilised, not reduced, when iron is scarce.

Why is "Ferritin translation rises and transferrin receptor mRNA is degraded" not the answer?

This is the pattern seen in iron-replete cells.

What concept does this question test?

It tests Vitamins and minerals: iron regulatory proteins in Biochemistry. The cell therefore stores less iron and takes up more. With iron excess the opposite occurs.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Vitamins and minerals: iron regulatory proteins?

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.