Read the following passage carefully and answer the given questions.
Insulin consists of two short polypeptide chains- chain A and chain B, that are linked together by disulphide bridges. Some strains of Bacillus thuringiensis produce proteins that kill certain insects such as lepidopterans, coleopterans and dipterans. Bt toxin protein is converted into an active form of toxin due to the alkaline pH of the gut which solubilise the crystals. Transgenic animals that produce useful biological products can be created by the introduction of the portion of DNA (or genes) which codes for a particular product such as human protein (α-1-antitrypsin) used to treat emphysema. Plants, bacteria, fungi and animals whose genes have been altered by manipulation are called Genetically Modified Organisms (GMO). GM plants have been useful in many ways. Genetic modification has: (i) made crops more tolerant to abiotic stresses. (ii) reduced reliance on chemical pesticides (pest-resistant crops). (iii) helped to reduce post harvest losses. (iv) increased efficiency of mineral usage by plants (this prevents early exhaustion of fertility of soil). (v) enhanced nutritional value of food.
Which one of the following is not true about insulin?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Insulin is used in diabetic patient in hypoglycemic condition.
Insulin is a hormone that lowers blood glucose. The passage says that it has two short polypeptide chains, A and B, linked by disulphide bridges. In the body, insulin is first made as a pro-hormone that has an extra stretch, the C peptide, which is removed during maturation.
Option (1) The main challenge for production of insulin using rDNA techniques was getting insulin assembled into a mature form. — True about insulin. In 1983 Eli Lilly made chains A and B separately in E. coli and then joined them by disulphide bonds to get mature human insulin.
Option (2) The two polypeptide chains in insulin are linked together by disulphide bridges. — True about insulin. Disulphide bridges hold chains A and B together. This is the form in which Eli Lilly joined the two chains made in E. coli.
Option (3) C-peptide is not present in mature insulin. — True about insulin. The C peptide is cut out when pro-insulin matures into insulin.
Option (4) Insulin is used in diabetic patient in hypoglycemic condition. — Not true about insulin. Diabetes causes high blood glucose (hyperglycemia). Insulin is given to bring the glucose down. In hypoglycemia the glucose is already low, so insulin would make it dangerously lower.
Note: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.
NCERT Extract:
Genetically Engineered Insulin – …
