Arrange the following steps which are involved in the production of insulin.
A. Production and extraction of chain A and B separately
B. Isolation of DNA sequences of chain A and B of human insulin
C. Joining of chain A and B by disulfide bonds to form human insulin
D. Insertion of DNA of chain A and B in plasmids of E. coli
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → B, D, A, C
(B) Isolation of DNA sequences of chain A and B of human insulin — comes first. Insulin is made of two short chains, A and B. The DNA sequences for each chain have to be prepared before anything else can be done.
(D) Insertion of DNA of chain A and B in plasmids of E. coli — comes second. A plasmid carries the foreign DNA into the bacterium.
(A) Production and extraction of chain A and B separately — comes third. The bacteria make the two chains in separate cultures, and the chains are then extracted.
(C) Joining of chain A and B by disulphide bonds to form human insulin — comes last. Only the joined chains are the mature, working hormone.
NCERT Extract:
Genetically Engineered Insulin – “… 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.”