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.
Which of the following organisms is used to produce genetically engineered insulin?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → E. coli
Genetically engineered insulin is made by bacteria. In 1983, Eli Lilly prepared two DNA sequences corresponding to chains A and B of human insulin and introduced them into plasmids of E. coli. The bacteria made the two chains separately; these were extracted and joined to form human insulin. Bacteria can be grown in large amounts, so as much insulin as needed can be made.
Option (1) Agrobacterium — Incorrect. Agrobacterium is used as a vector to put genes into plants, for example the nematode-specific genes put into tobacco.
Option (2) Transgenic mice — Incorrect. Transgenic mice are used to study diseases and to test the safety of vaccines, not to make insulin.
Option (3) E. coli — Correct. E. coli received the DNA sequences of chains A and B in its plasmids and produced the insulin chains.
Option (4) Transgenic cows — Incorrect. The transgenic cow Rosie produced milk enriched with a human protein, alpha-lactalbumin. Cows are not used for making 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.”