BRAINCAKEAntibiotic Resistance
Antibiotic resistance is the ability of bacteria to survive a dose of an antibiotic that would normally kill them or stop their growth. It is one of the clearest examples of natural selection happening today.
Resistance evolves in these steps:
1. In a large bacterial population, a random mutation may produce an allele that gives resistance, for example a gene for an enzyme that breaks down the antibiotic (penicillinase breaks down penicillin) or a change in the antibiotic's target site.
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Key terms in this lesson
- plasmid
- A small, circular loop of DNA in the cytoplasm of a bacterium, separate from the main chromosome, that can replicate independently.
- binary fission
- The asexual division of a prokaryotic cell into two genetically identical daughter cells.
More in Natural Selection
- Natural Selection in Moths
- Reproductive Success
- Directional Selection
- Antibiotics
- Preventing Antibiotic Resistance
- Speciation
- Types of Isolation
- Allopatric Speciation
All 29 lessons in Natural Selection · All Edexcel AS-level Biology topics