Translation: aminoglycosides: 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: aminoglycosides

Sample item

A patient with an intra-abdominal abscess containing Bacteroides fragilis shows no response to gentamicin alone. What is the biochemical reason?

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

The answer and the reasoning

A. Aminoglycoside entry needs an oxygen-dependent membrane potential, which anaerobes lack

Aminoglycosides bind the 30S subunit, cause misreading and block initiation, but they cross the bacterial membrane by an energy-dependent process linked to oxidative electron transport. Anaerobes lack this and are intrinsically resistant, so metronidazole or clindamycin is used for them.

Option by option

  • A. Aminoglycoside entry needs an oxygen-dependent membrane potential, which anaerobes lack (correct)

    Correct. Transport into the cell depends on aerobic respiration.

  • B. Gentamicin is destroyed by anaerobic metabolism in the abscess

    The drug is not inactivated by anaerobic metabolism, though low pH in abscesses reduces activity.

  • C. Gentamicin acts only on the 50S subunit

    Gentamicin acts on the 30S subunit; macrolides and chloramphenicol act on the 50S subunit.

  • D. Bacteroides lack a 30S ribosomal subunit

    All bacteria have 30S subunits, including anaerobes.

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 A, Aminoglycoside entry needs an oxygen-dependent membrane potential, which anaerobes lack. Aminoglycosides bind the 30S subunit, cause misreading and block initiation, but they cross the bacterial membrane by an energy-dependent process linked to oxidative electron transport.

Why is "Gentamicin is destroyed by anaerobic metabolism in the abscess" not the answer?

The drug is not inactivated by anaerobic metabolism, though low pH in abscesses reduces activity.

Why is "Gentamicin acts only on the 50S subunit" not the answer?

Gentamicin acts on the 30S subunit; macrolides and chloramphenicol act on the 50S subunit.

Why is "Bacteroides lack a 30S ribosomal subunit" not the answer?

All bacteria have 30S subunits, including anaerobes.

What concept does this question test?

It tests Translation: aminoglycosides in Biochemistry. Anaerobes lack this and are intrinsically resistant, so metronidazole or clindamycin is used for them.

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: aminoglycosides?

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.