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Selective breeding and genetic modification
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People have changed plants and animals for thousands of years. Now we can change genes directly.
Selective breeding
Choose parents with the desired characteristic, breed them, choose the best offspring and repeat over many generations.
Examples: high-yield wheat, cows that produce more milk.
Risk: less genetic variation, so a new disease could wipe out the whole population.
Examples: high-yield wheat, cows that produce more milk.
Risk: less genetic variation, so a new disease could wipe out the whole population.
Genetic engineering
A gene is cut from one organism using restriction enzymes and inserted into another, often using a plasmid as a vector. Ligase joins the DNA.
Example: bacteria that make human insulin.
Example: bacteria that make human insulin.
Benefits and risks
Benefits: pest-resistant crops, higher yields, crops with extra vitamins.
Risks: genes might spread to wild plants; long-term effects are uncertain; ethical concerns.
Risks: genes might spread to wild plants; long-term effects are uncertain; ethical concerns.
Give one advantage and one risk of selective breeding.
- Advantage: produces organisms with useful characteristics, like higher yields.
- Risk: reduces genetic variation, making the population vulnerable to disease.
Answer: More useful traits, but less variation.
Selective breeding chooses the best parents over many generations. Genetic engineering moves a gene using restriction enzymes, ligase and a vector. Both bring benefits and risks.
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