<prompt> Insulin has how many amino acids-25305171  <response>: 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. 