D) Preparing two DNA sequences corresponding to A and B chains of human insulin and introduced them in the plasmids of E. coli to produce insulin

Eli Lilly, an American company, is famous for preparing two DNA sequences corresponding to the A and B chains of human insulin and introducing them into the plasmids of Escherichia coli (E. coli) bacteria in order to produce insulin. This process is commonly known as recombinant DNA technology or genetic engineering.

Recombinant DNA Technology:
Recombinant DNA technology involves the manipulation of DNA molecules to create new combinations of genetic material. In this case, Eli Lilly prepared two DNA sequences corresponding to the A and B chains of human insulin. The A and B chains are specific protein sequences that make up the structure of insulin.

Introduction into E. coli:
E. coli bacteria are commonly used in genetic engineering due to their ability to rapidly reproduce and express foreign genes. Eli Lilly introduced the prepared DNA sequences into the plasmids of E. coli. Plasmids are small, circular DNA molecules found in bacteria that can replicate independently from the bacterial chromosome.

Production of Insulin:
Once the DNA sequences were successfully introduced into the plasmids of E. coli, the bacteria were allowed to multiply and express the insulin genes. This resulted in the production of the A and B chains of human insulin within the bacterial cells.

Isolation and Purification:
After the bacteria expressed the insulin genes, the A and B chains of human insulin were isolated and purified from the bacterial cells. This process involved disrupting the bacterial cells and separating the insulin chains from other cellular components.

Combining A and B Chains:
Once the A and B chains of human insulin were isolated and purified, they were combined to form the complete insulin molecule. The A and B chains are linked together by disulfide bonds, resulting in the final structure of insulin.

Medical Applications:
The production of insulin through recombinant DNA technology has revolutionized the treatment of diabetes. Insulin produced using this method is identical to human insulin and can be used to effectively regulate blood sugar levels in individuals with diabetes.

In conclusion, Eli Lilly is famous for its contribution to the production of insulin through recombinant DNA technology. This process involves preparing DNA sequences corresponding to the A and B chains of human insulin and introducing them into the plasmids of E. coli bacteria to produce insulin. This innovation has greatly improved the lives of individuals with diabetes.

Eli Lilly marketed the first human insulin, Humulin, in 1982. Humulin was the first medication produced using modern genetic engineering techniques in which actual human DNA is inserted into a host cell (E. coli). The host cells are then allowed to grow and reproduce normally, and due to the inserted human DNA through plasmids, they produce a synthetic version of human insulin.