BRAINCAKEAntibiotics
An antibiotic is a chemical that kills bacteria or stops them growing, without harming the cells of the host. Many antibiotics were first found as substances made by microorganisms (penicillin comes from the fungus Penicillium), although many are now made or modified in the laboratory.
Antibiotics are described by their effect:
Bactericidal antibiotics kill bacteria. Penicillin is bactericidal: it inhibits the enzymes that form cross-links in peptidoglycan. As the bacterium grows, its wall becomes weak, water enters by osmosis and the cell bursts (osmotic lysis).
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Key terms in this lesson
- selective toxicity
- The ability of a drug to harm or kill a pathogen while causing little or no harm to the host's own cells.
More in Prokaryotic Cells
- Plasmids
- Nucleoid
- 70S Ribosomes
- Gram-Staining
- Alternative Classification of Bacteria
- Viruses
- The Structure of Viruses
- DNA Viruses
All 31 lessons in Prokaryotic Cells · All Edexcel AS-level Biology topics