Final answer:
The action of beta-lactam antibiotics on penicillin-binding proteins (PBPs) is irreversible.
Step-by-step explanation:
The action of beta-lactam antibiotics on penicillin-binding proteins (PBPs) is irreversible.
Penicillin, a member of the beta-lactam class of antibiotics, irreversibly inhibits the enzyme transpeptidase, which is involved in the formation of peptide crosslinks in the bacterial cell wall. The beta-lactam ring in penicillin binds irreversibly to the enzyme's active site, rendering it inactive and preventing the formation of new peptide crosslinks. This ultimately leads to the degradation and lysis of bacterial cells.
Thus, the correct answer is B) Irreversible.