Penicillin exerts its antibacterial effect by which mechanism?

Penicillin exerts its antibacterial effect by which mechanism?

• A. Inhibition of Protein Synthesis at the 30S Ribosomal Subunit
• B. Reduction of Dihydrofolic Acid
• C. Inhibition of Peptidoglycan Synthesis
• D. Inhibition of Nucleic Acid Function

Answer: (C)

Penicillin acts by blocking the construction of the bacterial cell wall. It does this by binding to penicillin-binding proteins, the enzymes that normally catalyze the final cross-linking steps (transpeptidation) in peptidoglycan synthesis. Without these cross-links, the cell wall becomes weak, and actively growing bacteria cannot withstand osmotic pressure, leading to cell lysis. This mechanism is specific to bacteria with peptidoglycan in their walls, explaining the selective toxicity for bacteria over human cells. This is different from blocking protein synthesis at the ribosome, which would affect translation; inhibiting dihydrofolic acid disrupts folate synthesis; and interfering with nucleic acid function targets DNA/RNA processes.

Penicillin acts by blocking the construction of the bacterial cell wall. It does this by binding to penicillin-binding proteins, the enzymes that normally catalyze the final cross-linking steps (transpeptidation) in peptidoglycan synthesis. Without these cross-links, the cell wall becomes weak, and actively growing bacteria cannot withstand osmotic pressure, leading to cell lysis. This mechanism is specific to bacteria with peptidoglycan in their walls, explaining the selective toxicity for bacteria over human cells.

This is different from blocking protein synthesis at the ribosome, which would affect translation; inhibiting dihydrofolic acid disrupts folate synthesis; and interfering with nucleic acid function targets DNA/RNA processes.