Which functional group is characteristic of beta-lactam antibiotics like penicillin?
- Ester
- Amide
- Beta-lactam ring
- Carboxylic acid
Answer: Beta-lactam ring
Beta-lactam ring (4-membered cyclic amide) inhibits bacterial cell wall synthesis. Resistance via beta-lactamase enzymes. Core structure for penicillins, cephalosporins, carbapenems. [[NCERT Chemistry Class 12]]