Evolution in Bacteria
- The theory of evolution by natural selection is now widely accepted and many sources of data are now available to support the theory of evolution
- One very clear piece of evidence for evolution is antibiotic resistance in bacteria
- An antibiotic is a chemical that can kill or inhibit the growth and reproduction of bacteria
- Antibiotics are extremely useful to humans as some bacteria are pathogenic and can cause life-threatening disease
- Bacteria reproduce, on average, every 20 minutes and therefore evolution occurs in a much shorter time span
- Like all other organisms, within a population, there will be variation caused by mutations
- A chance mutation might cause some bacteria to become resistant to an antibiotic (eg penicillin)
- When the population is treated with this antibiotic, the resistant bacteria do not die
- This means they can continue to reproduce with less competition from non-resistant bacteria, which are now dead
- Therefore the genes for antibiotic resistance are passed on with a much greater frequency to the next generation
- Over time the whole population of bacteria becomes antibiotic-resistant because the bacteria are best suited to their environment
