What part of penicillin kills bacteria?

What part of penicillin kills bacteria?

• A. Beta-lactam ring
• B. Thiazolidine ring
• C. Carboxyl group
• D. Amino side chain

Answer: (A)

The part that does the killing is the beta-lactam ring. This four-membered ring resembles the reactive end of the bacterial cell-wall building blocks, so it binds to penicillin-binding proteins and blocks the transpeptidase enzyme that cross-links peptidoglycan strands. That interference prevents proper cell-wall synthesis, leaving the wall weak and leading to bacterial lysis, especially in environments where the cell wall is under stress. The other features—the thiazolidine ring, carboxyl group, and amino side chain—help with stability, pharmacokinetics, and the drug’s spectrum, but they aren’t the portion that directly stops cell-wall construction.

The part that does the killing is the beta-lactam ring. This four-membered ring resembles the reactive end of the bacterial cell-wall building blocks, so it binds to penicillin-binding proteins and blocks the transpeptidase enzyme that cross-links peptidoglycan strands. That interference prevents proper cell-wall synthesis, leaving the wall weak and leading to bacterial lysis, especially in environments where the cell wall is under stress. The other features—the thiazolidine ring, carboxyl group, and amino side chain—help with stability, pharmacokinetics, and the drug’s spectrum, but they aren’t the portion that directly stops cell-wall construction.