Insulin has how many amino acids-

Ans. is 'c' i.e., 51 * Insulin is a polypeptide hormone which is synthesized as a larger preprohormone (preproinsulin). As the preprohormone enters the endoplasmic reticulum, 23 amino-acid signal peptide is removed and it is converted to prohormone (proinsulin).* Proinsulin is made up A and B chain connected by a connecting peptide (C-peptide or C-chain). C-peptide is detached in the granules before secretion. Normally, 90-97% of the product released from B cells is insulin along with equimolar amounts of C-peptide.* Insulin is a two chain polypeptide having 51 aminoacids: The A chain has 21 while B-chain has 30-aminoacids.* Half life of insulin is about 5 minutes.