Antibiotics work without harming surrounding human cells because they specifically target features and processes unique to bacterial cells that are either absent or structurally different in human cells. The main targets of antibiotics in bacteria are:
- The bacterial cell wall or membranes, which human cells do not have.
- The machinery that produces nucleic acids (DNA and RNA).
- The machinery that produces proteins (such as the bacterial ribosome).
Because these targets are either absent or sufficiently different in human cells, antibiotics can disrupt bacterial growth or kill bacteria without damaging human cells. However, some antibiotics can still have side effects due to other mechanisms or interactions in the body. In summary, antibiotics exploit fundamental differences in cell structure and function between bacteria and human cells to selectively destroy bacteria while sparing human cells.
