Which of the following best describes the action of penicillins on bacteria?

Penicillins are a class of antibiotics that primarily function by inhibiting cell wall synthesis in bacteria. This mechanism is vital because the bacterial cell wall is crucial for maintaining structural integrity and shape. Penicillins target a specific component of the cell wall known as peptidoglycan, which is unique to bacteria. By binding to penicillin-binding proteins (PBPs) involved in the synthesis and cross-linking of peptidoglycan, penicillins weaken the cell wall. This ultimately leads to cell lysis and death, especially in actively dividing bacteria that are in the process of building new cell walls.

In contrast, options suggesting inhibition of protein synthesis or interference with nucleic acid replication describe mechanisms relevant to other antibiotic classes, such as tetracyclines or fluoroquinolones, respectively. The disruption of cell membrane function is also a characteristic of different antimicrobial agents, such as polymyxins. Therefore, the action of penicillins specifically and effectively describes their role in cell wall synthesis inhibition, making this the most accurate option.