Arrange the following steps of genetically engineered insulin production.
(A) Isolation and purification of the insulin gene from beta cells of the pancreatic islets
(B) Expression of gene in host cell
(C) Joining the two polypeptides by disulfide bonds
(D) Cloning of insulin gene in Escherichia coli cloning host cell
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A), (D), (B), (C)
(A) Isolation and purification of the insulin gene — first. The DNA for the insulin chains is prepared; insulin is made of two short chains, A and B.
(D) Cloning of insulin gene in Escherichia coli — second. The DNA is put into plasmids of E. coli, which carry it into the bacteria.
(B) Expression of gene in host cell — third. The bacteria make the A and B chains, separately, which are then extracted.
(C) Joining the two polypeptides by disulfide bonds — last. The two chains are joined by disulphide bridges to form mature 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.”