Which of the following statements is/are incorrect?

None of the above.

The correct answer is Option (4) -None of the above.

In the past, insulin used for diabetes treatment was derived from the pancreas of slaughtered cattle and pigs. However, this animal-source insulin sometimes caused patients to develop allergies or other reactions due to the foreign proteins present in it.

Insulin is composed of two short polypeptide chains, namely chain A and chain B, which are connected by disulfide bridges.

In mammals, including humans, insulin is initially produced as a prohormone, similar to a proenzyme that requires processing to become a fully mature and functional hormone. This prohormone contains an additional segment called the C-peptide. However, during the maturation process into insulin, the C-peptide is removed, and it is not present in the mature insulin.

The main challenge in producing insulin using recombinant DNA (rDNA) techniques was achieving the assembly of insulin into its mature form. In 1983, the American company Eli Lilly prepared two DNA sequences corresponding to the A and B chains of human insulin and introduced them into plasmids of Escherichia coli (E. coli) bacteria to produce insulin chains. The A and B chains were generated separately, extracted, and then combined by creating disulfide bonds to form human insulin. This process allowed for the production of synthetic human insulin through rDNA technology, providing a safer and more reliable source of insulin for diabetes management.