BRAINCAKEAntibiotics
Antibiotics are chemicals that kill bacteria or slow their growth without harming the cells of the person taking them. Many were first found in fungi and other bacteria; for example, penicillin was discovered from the mould Penicillium.
Antibiotics work because bacterial (prokaryotic) cells have structures and enzymes that human (eukaryotic) cells do not, so the drug can target these differences. Common targets are:
1. Cell wall synthesis. Penicillin stops bacteria forming the cross-links in their peptidoglycan cell wall. As the bacterium grows, the weakened wall cannot resist the pressure of water entering by osmosis, so the cell bursts (lysis). Human cells have no cell wall, so they are unaffected.
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Key terms in this lesson
- peptidoglycan
- A polymer of sugars cross-linked by short chains of amino acids that forms the cell wall of bacteria, giving it strength and shape.
More in Natural Selection
- Natural Selection in Oysters
- Natural Selection in Moths
- Reproductive Success
- Directional Selection
- Antibiotic Resistance
- Preventing Antibiotic Resistance
- Speciation
- Types of Isolation
All 29 lessons in Natural Selection · All Edexcel AS-level Biology topics