Which drug is a classic example of a 50S ribosome inhibitor?

Which drug is a classic example of a 50S ribosome inhibitor?

• A. Macrolides
• B. Aminoglycosides
• C. Tetracyclines
• D. Fluoroquinolones

Answer: (A)

The main concept here is recognizing which antibiotic class targets the 50S ribosomal subunit to stop protein synthesis. Macrolides are a classic example because they bind to the 23S rRNA in the 50S subunit and block the translocation step, so the growing peptide chain cannot move from the A site to the P site. This halts elongation and effectively shuts down protein synthesis. That’s why they’re considered 50S inhibitors. In contrast, aminoglycosides and tetracyclines target the 30S subunit and disrupt tRNA binding or cause misreading, while fluoroquinolones disrupt DNA replication by inhibiting DNA gyrase/topoisomerase. So macrolides best fit as the classic 50S ribosome inhibitor.

The main concept here is recognizing which antibiotic class targets the 50S ribosomal subunit to stop protein synthesis. Macrolides are a classic example because they bind to the 23S rRNA in the 50S subunit and block the translocation step, so the growing peptide chain cannot move from the A site to the P site. This halts elongation and effectively shuts down protein synthesis. That’s why they’re considered 50S inhibitors. In contrast, aminoglycosides and tetracyclines target the 30S subunit and disrupt tRNA binding or cause misreading, while fluoroquinolones disrupt DNA replication by inhibiting DNA gyrase/topoisomerase. So macrolides best fit as the classic 50S ribosome inhibitor.