Transcription: RNA polymerase II inhibition: 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 · Transcription: RNA polymerase II inhibition

Sample item

A family in a hill district eats wild mushrooms and, after 8 hours of vomiting and watery diarrhoea, one member improves briefly and then develops jaundice and hepatic failure on day 3. The toxin is Amanita phalloides alpha-amanitin. Which cellular process does it block?

ASynthesis of mRNA by eukaryotic RNA polymerase IIBSynthesis of tRNA by RNA polymerase IIICSynthesis of ribosomal RNA by RNA polymerase IDElongation of the polypeptide chain at the ribosome

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

The answer and the reasoning

A. Synthesis of mRNA by eukaryotic RNA polymerase II

Alpha-amanitin binds RNA polymerase II strongly and stops mRNA synthesis, so protein synthesis fails in cells with high turnover, especially hepatocytes and enterocytes. RNA polymerase III is inhibited only at high concentrations, and polymerase I is insensitive. Supportive care and early liver transplantation assessment are important.

Option by option

A. Synthesis of mRNA by eukaryotic RNA polymerase II (correct)
Polymerase II makes mRNA, and its blockade explains hepatocyte necrosis.
B. Synthesis of tRNA by RNA polymerase III
RNA polymerase III makes tRNA and 5S rRNA and is inhibited only at much higher concentrations.
C. Synthesis of ribosomal RNA by RNA polymerase I
RNA polymerase I makes rRNA and is not inhibited by amanitin.
D. Elongation of the polypeptide chain at the ribosome
Translation elongation is not the primary target of this toxin.

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.

Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is A, Synthesis of mRNA by eukaryotic RNA polymerase II. Alpha-amanitin binds RNA polymerase II strongly and stops mRNA synthesis, so protein synthesis fails in cells with high turnover, especially hepatocytes and enterocytes.

Why is "Synthesis of tRNA by RNA polymerase III" not the answer?

RNA polymerase III makes tRNA and 5S rRNA and is inhibited only at much higher concentrations.

Why is "Synthesis of ribosomal RNA by RNA polymerase I" not the answer?

RNA polymerase I makes rRNA and is not inhibited by amanitin.

Why is "Elongation of the polypeptide chain at the ribosome" not the answer?

Translation elongation is not the primary target of this toxin.

What concept does this question test?

It tests Transcription: RNA polymerase II inhibition in Biochemistry. RNA polymerase III is inhibited only at high concentrations, and polymerase I is insensitive. Supportive care and early liver transplantation assessment are important.

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 Transcription: RNA polymerase II inhibition?

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.