GENETIC ENGINEERING (also called recombinant DNA technology or genetic modification) is the direct manipulation of an organism's DNA — inserting, removing or modifying specific genes.
Unlike selective breeding, genetic engineering:
Can introduce genes from COMPLETELY DIFFERENT SPECIES — e.g. human genes into bacteria.
Works in a single generation — no need to wait many generations.
Is extremely precise — targets a specific gene.
The basic process:
1. The desired gene is CUT from the source organism's DNA using restriction enzymes (molecular scissors).
2. The gene is INSERTED into a VECTOR — usually a bacterial PLASMID (a small circular piece of DNA).
3. The vector is introduced into the target organism's cells.
4. The target organism's cells now EXPRESS the new gene — producing the desired protein.
Examples of Genetic Engineering
INSULIN PRODUCTION:
Human insulin gene inserted into BACTERIA.
Bacteria grow rapidly in large vats → produce large quantities of human insulin.
Used to treat Type 1 diabetes.
Before this (before ~1982), diabetics used insulin extracted from pig or cattle pancreases — which caused immune reactions in some patients.
Human insulin from GM bacteria is identical to natural human insulin → fewer side effects.
GM CROPS (Genetically Modified crops):
HERBICIDE RESISTANCE — a gene for herbicide resistance inserted into crop plants (e.g. GM soybean). Farmers can spray the field to kill weeds without harming the crop.
PEST RESISTANCE — Bt crops: a gene from the bacterium Bacillus thuringiensis produces a natural insecticide within the plant. Reduces need for chemical pesticides.
GOLDEN RICE — a gene from daffodils (and a bacterium) inserted into rice to produce beta-carotene (precursor to vitamin A). Addresses vitamin A deficiency in developing countries.
DROUGHT TOLERANCE — genes that increase water efficiency inserted into crops for use in dry regions.
Can save lives — GM insulin prevents deaths from diabetes.
Can increase food security — GM crops produce higher yields, resist disease and pests.
Can address nutritional deficiencies — e.g. Golden Rice.
May reduce environmental impact — pest-resistant crops need fewer chemical pesticides.
ARGUMENTS AGAINST:
UNCERTAINTY about long-term effects — what happens when GM organisms interact with wild ecosystems?
BIODIVERSITY risks — modified genes could spread to wild relatives ('gene escape').
MONOCULTURES — large-scale GM crop production may reduce genetic diversity.
CORPORATE CONTROL — major biotechnology companies own patents on GM seeds, preventing farmers from saving seeds.
ANIMAL WELFARE — concerns about use of genetically modified animals in research.
CONSUMER CONCERNS — some people don't want to eat GM food, regardless of scientific evidence of safety.
Religious/ethical objections — interfering with 'nature' or 'playing God'.
⚠️ Common Mistake
Genetic engineering is NOT the same as selective breeding. Genetic engineering can transfer genes between completely different species (e.g. human genes into bacteria). Selective breeding can only work with organisms that can naturally reproduce together. Also: eating GM food does not alter the consumer's own DNA.
📌 Key Note
Genetic engineering: cut gene with restriction enzymes → insert into vector (plasmid) → introduce to target organism. Examples: human insulin from GM bacteria, herbicide-resistant crops, Golden Rice. Ethical debate: benefits vs risks to biodiversity and ecosystems.
🎯 Matching Activity — Match the Genetic Engineering Example
Match each application to how genetic engineering is used. — drag the symbols on the right to match the component names on the left.
GM bacteria → insulin
Drop here
Herbicide-resistant crops
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Bt crops
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Golden Rice
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Gene inserted to produce beta-carotene — addresses vitamin A deficiency in developing countries
Human insulin gene inserted into bacteria — bacteria produce insulin for diabetics
Gene for herbicide resistance inserted into crop plants — farmer can spray without harming the crop
Gene from Bacillus thuringiensis inserted — crop produces natural insecticide to repel pests
🎯 Test Yourself
Question 1 of 2
1. Why is GM bacterial insulin better for diabetics than insulin extracted from pigs or cattle?
2. What is the basic process of introducing a new gene into an organism?
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