Translation: aminoacyl-tRNA synthetase: 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 · Translation: aminoacyl-tRNA synthetase

Sample item

A topical antibiotic used to clear nasal carriage of MRSA inhibits the bacterial enzyme that loads isoleucine onto its transfer RNA. Which enzyme class is the target?

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

The answer and the reasoning

A. Aminoacyl-tRNA synthetase

Mupirocin competitively inhibits bacterial isoleucyl charging, so protein synthesis stops, and it is useful because it has no cross-resistance with other classes. It is used topically because it is rapidly inactivated systemically. Peptidyl transferase is blocked by chloramphenicol.

Option by option

  • A. Aminoacyl-tRNA synthetase (correct)

    Correct. Mupirocin blocks bacterial isoleucyl charging of transfer RNA.

  • B. Elongation factor G

    Elongation factor G is the translocation factor blocked by fusidic acid.

  • C. Peptidyl transferase

    Peptidyl transferase is the target of chloramphenicol, not mupirocin.

  • D. DNA gyrase

    DNA gyrase is inhibited by fluoroquinolones.

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, Aminoacyl-tRNA synthetase. Mupirocin competitively inhibits bacterial isoleucyl charging, so protein synthesis stops, and it is useful because it has no cross-resistance with other classes.

Why is "Elongation factor G" not the answer?

Elongation factor G is the translocation factor blocked by fusidic acid.

Why is "Peptidyl transferase" not the answer?

Peptidyl transferase is the target of chloramphenicol, not mupirocin.

Why is "DNA gyrase" not the answer?

DNA gyrase is inhibited by fluoroquinolones.

What concept does this question test?

It tests Translation: aminoacyl-tRNA synthetase in Biochemistry. It is used topically because it is rapidly inactivated systemically. Peptidyl transferase is blocked by chloramphenicol.

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 Translation: aminoacyl-tRNA synthetase?

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.