GCSE Biology · Edexcel 1BI0 · Topic 4D
Selective breeding and genetic engineering
Key points
- Selective breeding: humans choose parents with useful characteristics and breed them over many generations, e.g. high-yield crops or calm farm animals.
- Risks: a smaller gene pool (inbreeding) increases inherited disorders and makes a population more vulnerable to disease.
- Genetic engineering (GM) moves a gene from one organism into another, e.g. bacteria that make human insulin or crops that resist pests.
- Method: cut the gene out with restriction enzymes (leaving sticky ends), cut a plasmid vector with the same enzymes, join them with ligase, then put the plasmid into a bacterium.
- Benefits: higher yields, less pesticide use, medicines. Concerns: genes spreading to wild plants, effects on insects and food chains, long-term health effects and cost to farmers.
- Compare the two methods: selective breeding is slow and only uses alleles already in the species.
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Humans have changed other species for thousands of years by choosing which animals and plants to breed. Now we can also move genes directly between species. This sub-topic covers both methods and how to weigh up their benefits and risks.
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