Penicillin Targets Peptidoglycan Cross-Linking

Steps:

• Recall that bacterial cell walls contain peptidoglycan, a polymer providing structural integrity.
• Penicillin binds to penicillin-binding proteins (PBPs) like transpeptidases during cell wall synthesis.
• This binding blocks the enzyme's role in forming cross-links between peptidoglycan chains.
• Without cross-links, the cell wall weakens, leading to lysis and bacterial death.

Why B is correct:

• Penicillin specifically inhibits transpeptidase enzymes, preventing covalent cross-links in peptidoglycan as defined in bacterial cell wall biosynthesis.

Why the others are wrong:

• A: Penicillin does not affect water uptake; that's more related to osmotic pressure changes post-wall damage.
• C: Penicillin does not inhibit hydrolysis; autolysins handle peptidoglycan breakdown during growth.
• D: Penicillin does not digest peptidoglycan; it blocks new synthesis, not enzymatic degradation.

Final answer: B