Arrange the following steps of genetically engineered insulin production in correct sequence.
A. Preparation of two DNA sequences corresponding to A and B chains and their insertion into E. coli plasmids
B. Extraction of two chains
C. Synthesis of both chains separately
D. Joining of both insulin chains by disulfide bonds
Which is the correct sequence?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → A, C, B, D
A. Preparation of two DNA sequences and their insertion into E. coli plasmids — first. Insulin is made of two short chains, A and B. In 1983 Eli Lilly prepared two DNA sequences for these chains and put them into plasmids of E. coli.
C. Synthesis of both chains separately — second. The bacteria made the A chain and the B chain separately.
B. Extraction of two chains — third. The two chains were then taken out of the bacteria.
D. Joining of both insulin chains by disulfide bonds — last. The chains were joined by disulfide bonds to form human insulin.
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.”