Final answer:
Penicillin inhibits bacterial cell wall synthesis by targeting enzymes involved in the construction of the cell wall, leading to bacterial cell bursting and eventually, bacterial death.
Step-by-step explanation:
Penicillin works by inhibiting the synthesis of bacterial cell walls. It binds to and inactivates enzymes that are critical for the cross-linking of peptide chains in the peptidoglycan layer, which is essential for maintaining cell wall integrity. This action renders the bacteria unable to prevent water from flowing into the cell, thus causing the cell to burst. As penicillins mainly affect actively dividing cells, they are most effective during the log phase when bacterial growth and division is most rapid. This mode of action does not affect human cells, since human cells do not have cell walls, exemplifying selective toxicity.
Cell wall synthesis inhibitors like penicillin are particularly useful because of their specificity for bacterial cells, reflecting a considerable therapeutic advantage. The semisynthetic derivatives of penicillin such as penicillin G and penicillin V, along with their broad-spectrum variants, are tailored to combat a wider range of bacteria effectively. As a result, penicillin and its derivatives remain central to antibiotic therapy and bacterial infection management.