Why are bacteria used to produce recombinant human insulin?

• A. They can express the human insulin gene and produce insulin in large amounts.
• B. They naturally contain the insulin gene and secrete it.
• C. They are immune to viral infections.
• D. They modify insulin to be more potent.

Answer: (A)

Recombinant DNA technology lets bacteria act as tiny factories for human proteins. By inserting the human insulin gene into a plasmid and introducing that plasmid into bacteria, the cells use their own machinery to read the gene and produce insulin, which can then be purified for medical use. The major advantage is speed and cost: bacteria multiply rapidly and cheaply, so large amounts of insulin can be produced in fermenters. This works because the insulin gene can be carried and expressed outside human cells, yielding the correct protein product. The other statements don’t fit because bacteria don’t naturally contain or secrete insulin, and the goal isn’t immunity to viruses or altering insulin’s potency, but producing the human protein in quantity.