Genetic modification

Biology · Biotechnology and genetic modification. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.

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The idea

Genetic modification means changing the genetic material of an organism by removing, changing or inserting individual genes. The gene often comes from a different species.

The best known example is human insulin. The human gene that controls insulin production is inserted into bacterial DNA. The bacteria reproduce rapidly in a fermenter, and all of them make human insulin, which is collected and purified for people with diabetes.

Crop plants are also modified. Genes can be inserted to make a crop resistant to a herbicide, resistant to insect pests, or richer in vitamins. You should be able to give both advantages and risks.

Rules to remember

Genetic modification: changing genetic material by removing, changing or inserting individual genes.
Insulin: human insulin gene → inserted into bacterial DNA (a plasmid) → bacteria multiply → insulin is produced on a large scale.
Herbicide-resistant crop: the farmer can spray the field and kill the weeds without harming the crop, so there is less competition and a higher yield.
Insect-resistant crop: the plant makes a substance that kills the pests feeding on it, so less insecticide is sprayed and less of the crop is lost.
Extra vitamins: improves the diet and reduces deficiency diseases, for example rice with added vitamin A.
Risks: inserted genes may spread to wild plants in pollen (herbicide-resistant weeds); useful insects may be harmed; seed can be expensive; long-term effects are uncertain.

Common mistake

Genetic modification is not the same as selective breeding. Selective breeding crosses whole organisms over many generations; genetic modification moves individual genes directly.

Worked example

Farmer X crosses his two highest-yielding maize plants and keeps the best offspring each year. Company Y inserts a gene from a bacterium into maize so that it makes a substance that kills insect pests. Which is genetic modification?

Genetic modification means removing, changing or inserting individual genes.
Farmer X only chooses which plants breed. No single gene is moved. This is artificial selection.
Company Y inserts one gene from another species into the maize DNA.

Answer: Only company Y is using genetic modification.

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