Tetracycline inhibits bacterial protein synthesis. Its precise site of action is:

• A Causing misreading of mRNA codons at the 30S subunit
• B Binding the 50S subunit and inhibiting peptidyl transferase
• C Binding the 50S subunit and preventing translocation of the peptidyl-tRNA
• D Binding the 30S subunit and blocking aminoacyl-tRNA entry into the A site ✓

Explanation

Tetracyclines bind the 30S ribosomal subunit and block access of aminoacyl-tRNA to the acceptor (D) site, halting elongation. Chloramphenicol inhibits peptidyl transferase at the 50S subunit, macrolides such as erythromycin block translocation at the 50S subunit, and aminoglycosides cause codon misreading while also inhibiting initiation at the 30S subunit. Distinguishing the ribosomal subunit and the step affected separates these four antibiotic classes, a standard exam comparison.

Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.