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Before genetic engineering, insulin was obtained from pigs and cattle.

Due to an increase in the number of diabetics, more insulin is required than ever before.

Process

1. The human insulin gene is removed using a restriction enzyme.
2. A bacterial plasmid is cut open using the same restriction enzyme.
3. Restriction enzymes leave ‘sticky ends’, where one of the two DNA strands is longer than the other.
4. Using the same restriction enzyme to cut both the human DNA and bacterial plasmid results in complementary sticky ends that join by base pairing.
5. A different enzyme is used to join the insulin gene and the bacterial plasmid.
6. The bacterial plasmid containing the insulin gene is placed into a bacterial cell.
7. The bacterial cell is placed in a fermenter to allow reproduction under perfect conditions (warmth, moisture and oxygen).
8. Downstreaming occurs – this is when insulin is extracted, purified and packaged.
9. The pure insulin produced can be used to treat diabetes.

Advantages of genetically engineered insulin:

• Not limited by the slaughter of animals.
• Large quantities can be made quickly.
• No risk of transferring infections.
• More effective at treating diabetes as animal insulin is different to human insulin.
• No ethical issues concerning the use of animals.