Read the given passage and answer the following questions:
Managing diabetes is possible by administering insulin periodically. Insulin used for diabetes was earlier extracted from pancreas of slaughtered cattle and pigs. However, this insulin caused some people to develop allergies and other types of reactions. In mammals, including humans, insulin is synthesised as a prohormone and is later converted to insulin. Insulin consists of two short polypeptide chains: chain A and chain B, that are linked together by disulphide bridges.
Given below are two statements:
Statement I: The main challenge for production of insulin using rDNA techniques was getting insulin assembled into a mature form.
Statement II: In the rDNA method of making human insulin, chains A and B were produced separately and extracted before they were combined.
In the light of the above statements, choose the most appropriate answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Both Statement I and Statement II are true
Making human insulin by recombinant DNA technology was not only a matter of putting a gene into bacteria. The hormone had to be obtained in its mature form, with its two chains correctly joined.
Statement I: The main challenge for production of insulin using rDNA techniques was getting insulin assembled into a mature form. — True. In the body, insulin is made as pro-insulin and then processed into the mature hormone. Bacteria do not do this processing, so assembling the mature form was the main difficulty.
Statement II: In the rDNA method of making human insulin, chains A and B were produced separately and extracted before they were combined. — True. The DNA sequences for the two chains were put into E. coli separately. Chains A and B were produced separately, extracted and then combined by creating disulphide bonds. This is how the challenge in Statement I was met.
NCERT Extract:
Genetically Engineered Insulin – “… The main challenge for production of insulin using rDNA techniques was getting insulin assembled into a mature form. In 1983, Eli Lilly an American company prepared two DNA sequences corresponding to A and B, chains of human insulin and introduced them in plasmids of E. coli to produce insulin chains. Chains A and B were produced separately, extracted and combined by creating disulfide bonds to form human insulin.”