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GCSE OCR Gateway Natural selection and evolutionGenetic variation, as well as changes in the environment, cause characteristics of organisms to change over time. This process of natural selection leads to the evolution of new species. Part of Biology (Single Science) Genes, inheritance and selection
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Evidence for evolution - antibiotic resistance in bacteriaAntibiotic resistanceBacteria can evolve quickly because they reproduce at a fast rate. Mutations in the DNA of bacteria can produce new characteristics. A random mutation might cause some bacteria to become resistant to certain antibiotics, such as penicillin. Antibiotics usually kill bacteria, but in this case the mutation means the bacteria cannot be destroyed by the antibiotic. The emergence of antibiotic resistance in bacteria is an example of natural selectionleading to evolution. Development of antibiotic resistance Penicillin was the first antibiotic to be produced on a mass scale in the 1940s. It is derived from Penicillium fungi, shown here growing on an agar plate. Many new types of antibiotics were discovered during the 1950s and 1960s, but the rate of discovery has slowed greatly more recently. Many scientists even stopped looking for new antibiotics, as they felt it was unnecessary. Recent concerns about increasing antibiotic resistance have created a drive for new antibiotics. However, their development is costly and takes a long time. Some scientists fear that we are fighting a losing battle against antibiotic resistant bacteria, which may ultimately lead to people dying from simple infections.
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What type of evolution causes antibiotic resistance?Biological Mutations
Through mutation and selection, bacteria can develop defense mechanisms against antibiotics. For example, some bacteria have developed biochemical “pumps” that can remove an antibiotic before it reaches its target, while others have evolved to produce enzymes to inactivate the antibiotic.
How is antibiotic resistance an example of observable evolution?Evolutionary trade-offs occur when changes in a given gene or trait increase fitness in one environment but reduce fitness in another. For example, a history of adaptation to one antibiotic could alter resistance and subsequent evolution in the presence of a subsequent antibiotic.
What is antibiotic resistance and how does it show evolution?Resistance to antimicrobial treatments, also known as AMR, evolves rapidly, often over the course of a single infection. It occurs either by bacteria exchanging with one another the genes that confer resistance, or by an individual bacterium becoming resistant through mutations in its own genes.
How is antibiotic resistance an example of natural selection?Mutations can result in antibiotic resistance in bacteria. Resistant bacteria survive antibiotic treatment and can increase in numbers by natural selection.
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