Q.How many amino acids are arranged in the two chains of Insulin? a) Chain A has 12 and Chain B has 13 b) Chain A has 21 and Chain B has 30 amino acids c) Chain A has 20 and chain B has 30 amino acids d) Chain A has 12 and chain B has 20 amino acids

Human insulin is a two-chain protein hormone (a 21-amino-acid A chain and a 30-amino-acid B chain linked by disulphide bonds) made by the pancreatic beta cells, and it enables cells to take up glucose from the blood. Its deficiency causes diabetes mellitus. Before recombinant technology, insulin was purified from pig and cow pancreases, and minor structural differences from human insulin caused allergic reactions in some patients. From the late 1970s, the human insulin gene has instead been inserted into E. coli plasmids: the engineered bacteria first produce a single precursor chain, pre-pro-insulin, with a leader sequence and a connecting C-chain; the leader sequence is …