Penicillin's primary mechanism is to inhibit what aspect of bacterial cell biology?

Penicillin's primary mechanism is to inhibit what aspect of bacterial cell biology?

• A. Inhibiting the formation of peptidoglycan cross-links in the cell wall
• B. Inhibiting DNA gyrase
• C. Inhibiting the 30S ribosomal subunit
• D. Disrupting cell membrane permeability

Answer: (A)

Penicillin works by blocking the final steps of cell wall construction, specifically inhibiting penicillin-binding proteins that act as transpeptidases to cross-link peptidoglycan strands. Without these cross-links, the cell wall cannot maintain its structural integrity, and the bacterium becomes susceptible to lysis as it grows. This is most effective in actively dividing bacteria, where cell wall synthesis is ongoing. In contrast, drugs that inhibit DNA gyrase interfere with DNA replication, those that target the 30S ribosomal subunit disrupt protein synthesis, and agents that disrupt membrane permeability compromise the cell membrane—mechanisms not associated with penicillin.

Penicillin works by blocking the final steps of cell wall construction, specifically inhibiting penicillin-binding proteins that act as transpeptidases to cross-link peptidoglycan strands. Without these cross-links, the cell wall cannot maintain its structural integrity, and the bacterium becomes susceptible to lysis as it grows. This is most effective in actively dividing bacteria, where cell wall synthesis is ongoing. In contrast, drugs that inhibit DNA gyrase interfere with DNA replication, those that target the 30S ribosomal subunit disrupt protein synthesis, and agents that disrupt membrane permeability compromise the cell membrane—mechanisms not associated with penicillin.