Final answer:
Cephalosporins have increased resistance to beta-lactamases compared to penicillins due to a structural difference in their beta-lactam rings. The greater diversity in chemical alterations and development of semisynthetic forms in cephalosporins also sets them apart from penicillins.
Step-by-step explanation:
Cephalosporins differ from penicillins in their resistance to beta-lactamases, which are enzymes that break down beta-lactam antibiotics. Both cephalosporins and penicillins contain a beta-lactam ring, but the beta-lactam ring of cephalosporins is fused to a six-member ring, while the beta-lactam ring of penicillins is fused to a five-member ring. This structural difference provides cephalosporins with increased resistance to enzymatic inactivation by beta-lactamases. Additionally, cephalosporins have a greater diversity in chemical alterations and development of semisynthetic forms compared to penicillins.