Transcription: RNA polymerase II: 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

Sample item

The largest subunit of a nuclear enzyme carries a carboxy-terminal domain of repeated heptapeptides whose phosphorylation coordinates capping, splicing and polyadenylation of the nascent transcript. Which enzyme is this?

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

The answer and the reasoning

D. RNA polymerase II

The repeated heptapeptide tail of the largest subunit is phosphorylated during initiation and elongation, and serves as a platform to recruit capping, splicing and polyadenylation factors. This links transcription with RNA processing. Other polymerases lack this domain.

Option by option

  • A. Topoisomerase II

    Topoisomerase II relieves DNA supercoiling and does not synthesise RNA.

  • B. DNA polymerase delta

    DNA polymerase delta is a replicative enzyme with no role in transcript processing.

  • C. Poly(A) polymerase

    Poly(A) polymerase is a processing enzyme and has no such tail domain.

  • D. RNA polymerase II (correct)

    Correct. The phosphorylated tail recruits the processing machinery to the nascent transcript.

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 D, RNA polymerase II. The repeated heptapeptide tail of the largest subunit is phosphorylated during initiation and elongation, and serves as a platform to recruit capping, splicing and polyadenylation factors.

Why is "Topoisomerase II" not the answer?

Topoisomerase II relieves DNA supercoiling and does not synthesise RNA.

Why is "DNA polymerase delta" not the answer?

DNA polymerase delta is a replicative enzyme with no role in transcript processing.

Why is "Poly(A) polymerase" not the answer?

Poly(A) polymerase is a processing enzyme and has no such tail domain.

What concept does this question test?

It tests Transcription: RNA polymerase II in Biochemistry. This links transcription with RNA processing. Other polymerases lack this domain.

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?

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.