A level Biology B · Edexcel 9BI0 · Topic 7D
Genetic engineering
Key points
- Recombinant DNA is made by combining DNA from different organisms.
- The gene is cut out with restriction enzymes, which leave sticky ends, or made from mRNA using reverse transcriptase.
- The same restriction enzyme cuts a vector (e.g. a plasmid); DNA ligase joins the gene into it.
- The vector is taken up by host cells (e.g. by heat shock or electroporation); marker genes (e.g. antibiotic resistance or fluorescence) show which cells were transformed.
- Plants can be modified using Agrobacterium or a gene gun; animals by microinjection or viral vectors.
- Examples: bacteria making human insulin, pest-resistant crops, Golden Rice.
- Issues: risk of genes spreading to wild species, monoculture, corporate control of seeds, against benefits of higher yield and medicines.
Topic notesPremium
Genetic engineering moves a gene from one organism into another, so the receiver makes a new protein. It relies on enzymes that cut and join DNA, vectors that carry it, and markers that show which cells took it up.
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