Erythromycin interferes with protein synthesis by binding to which ribosomal subunit?

• A. 50S
• B. 60S
• C. 70S
• D. 80S

Answer: (A)

Erythromycin is an antibiotic that specifically targets the bacterial ribosome to inhibit protein synthesis. It binds to the 50S ribosomal subunit of the ribosome, which is essential for the process of translation in bacteria. By binding to this subunit, erythromycin prevents the translocation step of protein synthesis, ultimately halting the growth of bacteria.

In contrast, the other options refer to different ribosomal subunits found in various types of organisms. The 60S and 80S subunits are components of eukaryotic ribosomes (with 80S being the complete ribosome composed of both 40S and 60S subunits), while the 70S ribosome is found in prokaryotes but refers to the complete ribosomal complex rather than a specific subunit. Therefore, the specific action of erythromycin correlates with its binding to the 50S subunit, making that answer correct.