BRAINCAKECreating Drug-Resistant Bacteria
Antibiotics do not cause resistance mutations, but they select for bacteria that already carry them. This is natural selection:
1. A population of bacteria shows variation. A few cells carry an allele for resistance, which arose by chance mutation.
2. When the antibiotic is used, it acts as a selection pressure. Susceptible bacteria are killed or stop dividing.
3. Resistant bacteria survive and, with less competition, reproduce rapidly.
4. They pass the resistance allele on to their offspring, and to other bacteria by conjugation.
5. Over many generations the frequency of the resistance allele increases until most of the population is resistant.
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Key terms in this lesson
- allele
- One of the alternative forms of a gene, occupying the same position (locus) on a chromosome.
More in Bacteria and Disease
- Protein synthesis Inhibitors
- Cell Wall Agents
- Cell Membrane Agents
- DNA Gyrase Inhibitors
- Antibiotic Resistance
- MRSA
- Clostridium difficile
- Prevention and Control of Infection
All 30 lessons in Bacteria and Disease · All Edexcel A-level Biology topics