Which is correct regarding genetically engineered insulin using E. coli?
(A) Difficult to purify
(B) Obtained in large unlimited quantities
(C) Possibility of transmission of animal diseases
(D) Insulin obtained varies in chemical structure

Hint: Insulin is a protein that is responsible for decreasing the blood glucose level. The deficiency of Insulin leads to a disease known as Diabetes Mellitus. In Earlier days, insulin was extracted from the pancreas of pigs and cattles. Nowadays it is genetically engineered and obtained from E. coli. The genetically engineered Insulin is a proteinaceous hormone that has 51 Amino acids.

Complete answer:
In mammals, insulin is synthesized as a prohormone. The genetically engineered insulin has a special structure in which amino acids are arranged in two polypeptides A and B where A consist of 21 Amino acids and B has 30 amino acids respectively. The first genetically engineered insulin was produced by Eli-Lily on July 5, 1983. It was obtained by recombinant DNA technology with the help of E-Coli. The trade name given to this Insulin is ‘Humulin’. The major advantage of using E. coli in recombinants is that a large number of recombinant DNA can be produced even if only a limited amount of starting material is present. This serves as an efficient mechanism in the production of large amounts of genetically recombinant insulin without having to slaughter hundreds of cattle.

Therefore the correct option is (B) Obtain a large unlimited quantity.

Note: The first human Insulin was obtained by preparing two DNA sequences with correspondence to A and B polypeptide chains of Human insulin. They were then introduced into the plasmid vector of E. coli to produce insulin chains. These A and B chains were produced separately. These were later extracted and combined by creating disulphide bonds between them to form human Insulin.