Arrange the following steps in the production of human insulin by Eli Lilly in the correct sequence:
A. Chains A and B were combined by creating disulfide bonds.
B. Two DNA sequences corresponding to chains A and B of human insulin were prepared.
C. Chains A and B were produced separately and extracted.
D. The DNA sequences were introduced into plasmids of E. coli.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → B, D, C, A
Insulin is made of two short polypeptide chains, A and B, joined by disulphide bridges. In 1983 the American company Eli Lilly made human insulin by rDNA technology in four stages.
B. Two DNA sequences corresponding to chains A and B of human insulin were prepared. — First. The company began by preparing two separate DNA sequences, one coding for chain A and one for chain B.
D. The DNA sequences were introduced into plasmids of E. coli. — Second. The plasmids carried these sequences into E. coli, so the bacteria could make the insulin chains.
C. Chains A and B were produced separately and extracted. — Third. Each chain was made by the bacteria on its own and then taken out of them.
A. Chains A and B were combined by creating disulfide bonds. — Last. Only after both chains were ready could they be joined by disulphide bonds to give human insulin.
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.”