Human insulin for diabetic patients is now produced mainly by
- A. genetically engineered bacteria carrying the human insulin gene
- B. extraction from the pancreas of cattle and pigs
- C. chemical synthesis from amino acids in a factory
- D. collecting it from the urine of healthy donors
Explanation
The human gene is inserted into a bacterium such as Escherichia coli, which is then grown in a fermenter and makes insulin identical to the human hormone. This avoids the allergic reactions some patients had to insulin extracted from animals, removes any risk of transmitting animal disease and can be scaled to meet demand. Animal extraction was the older method it replaced.