Which molecular event explains the bactericidal action of aminoglycosides such as gentamicin?
- A Binding the 23S rRNA of the 50S subunit and blocking translocation
- B Blocking peptidyl transferase at the 50S acceptor site
- C Binding the 30S ribosomal subunit and causing misreading of mRNA codons ✓
- D Preventing formation of the initiation complex between mRNA and fMet-tRNA
Correct answer: C. Binding the 30S ribosomal subunit and causing misreading of mRNA codons
Explanation
Aminoglycosides bind irreversibly to the 30S ribosomal subunit near the A site and interfere with proofreading of the codon-anticodon match, so wrong amino acids are inserted and nonfunctional proteins accumulate. Option D describes aminoglycoside effect only partially at very low concentrations, while option C is the classic accepted answer. Option A describes macrolides and option B describes chloramphenicol and lincosamides.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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