Antibiotics work by targeting specific structures or processes that are unique to bacterial cells and not present in human cells. This selective targeting allows antibiotics to kill or inhibit bacteria without harming the surrounding human cells.
Selective Targets in Bacteria
- Antibiotics often inhibit bacterial cell wall synthesis. Human cells do not have cell walls; thus, drugs like beta-lactams bind to bacterial enzymes involved in forming the cell wall, causing bacterial death without affecting human cells.
- Some antibiotics disrupt bacterial cell membranes, which have a different composition from human cell membranes, allowing selective action.
- Antibiotics inhibit bacterial protein synthesis by binding to ribosomes. Bacterial ribosomes (70S, composed of 30S and 50S subunits) differ structurally from human ribosomes (80S), so drugs like tetracyclines and macrolides selectively target bacterial ribosomes to stop protein production without affecting human ribosomes.
- Other antibiotics interfere with bacterial DNA or RNA synthesis by inhibiting enzymes like DNA gyrase or RNA polymerase, which are different from those in human cells, ensuring selective toxicity.
This specificity in targeting bacterial structures or processes absent or significantly different in human cells explains how antibiotics avoid harming human cells while effectively combating bacterial infections.
