Final answer:
Erythromycin is a macrolide antibiotic that inhibits protein synthesis in bacteria by binding to their ribosomes and blocking peptide bond formation.
Step-by-step explanation:
Erythromycin, a macrolide antibiotic, inhibits protein synthesis by binding to the 50S ribosomal subunits of sensitive microorganisms. It specifically targets bacterial ribosomes and prevents peptide bond formation, thus stopping protein synthesis. Humans have ribosomes composed of 40S and 60S subunits, so erythromycin does not affect protein synthesis in human cells.