Explain why many antibiotics are effective only against cells that are actively

When cells are not actively growing and reproducing, they are not synthesizing many of their component molecules or structures. Because many antimicrobial drugs inhibit the synthesis of structures such as the cell wall or interfere with various metabolic pathways, cells that are not actively doing one or both of these activities will be naturally more resistant to these drugs. For example, as bacterial cells age or become dormant, they cease to synthesize molecules such as peptidoglycan; therefore, drugs such as penicillin, which act by inhibiting peptidoglycan synthesis, have no effect on these cells. Additionally, as cells age, they may modify or cease certain metabolic pathways. Drugs that target these pathways will thus lose their effect.