Drugs from genetically modified organismsSpec 8.17
In short
Genetically modified organisms can make human drugs. The human gene is inserted into a microorganism such as a bacterium or yeast, a plant or an animal, which makes the protein. Bacteria produce human insulin in fermenters, and transgenic animals and plants can make proteins in milk or leaves.
| Organism | How it is used | Example |
|---|---|---|
| Microorganisms (bacteria, yeast) | The human gene is inserted on a plasmid; the cells are grown in large fermenters and the protein is purified from the culture | Human insulin for diabetes; human growth hormone |
| Plants | A human gene is inserted into plant cells, and the protein is extracted from leaves or seeds | Antibodies and vaccine antigens made in tobacco or other plant leaves |
| Animals | The gene is joined to a promoter that works in the mammary gland, so the protein is secreted in milk | Human antithrombin (a protein that prevents unwanted blood clotting) in the milk of transgenic goats; human clotting factor IX in the milk of transgenic sheep |
Advantages of making human insulin in GM microorganisms rather than extracting it from animals:
- The insulin is identical to human insulin, so it is less likely to cause an immune response.
- It can be made in large amounts, quickly and cheaply, in fermenters.
- There are fewer ethical objections than using animals, and a reliable supply that does not depend on slaughter of animals.
Bacteria cannot remove introns and cannot modify proteins after translation in the way eukaryotic cells do (for example by adding carbohydrate groups). So a human gene for bacteria is supplied as cDNA, and proteins that need these modifications to work are made in yeast, plants or animals instead.
A ‘how are drugs produced using GMOs’ answer needs the sequence: isolate the human gene, insert it into a vector, put the vector in the host, express the gene and purify the protein.
Written and checked against the Edexcel International A Level Biology (YBI11) specification · Updated October 2026