This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Chemistry of Carbohydrates, Amino sugars, and Mucopolysaccharides, Subject name: Biochemistry
[{'content': 'True statement regarding insulin: \nSelect and explain. \nA. Produced by alpha cells of pancreas, B. Two polypeptide chains are bound by disulfide linkages, C. Shifts potassium outside the cell, D. S.c insulin tl/2 is 60 mins', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ref: Harper\'s Illustrated Biochemistry,28th editionExplanation:InsulinSecreted from pancreatic islet b cellsReleased regulated by blood (glycemic thresholdSynthesized as a single chain : pro-insulinInsulin is formed from proinsulin (removal of the connecting or "C" peptide)Insulin is thus made up of 2 chainsA (21 amino acids) and B (30 amino acids)Connected to each other by 2 inter disulfide bridges and 1 intra disulfide bridgeAll necessary for its hormone activity.ActionsStimulates glucose oxidation & storage and inhibits glucose productionStimulates glycogen synthaseInhibits phosph orylaseInhibits gluconeogenesisStimulates glucose transport into adipocytes, which is then converted intoTGInhibits hormone-sensitive lipase (HPL) (|cAMP) and lipoprotein lipaseActivates GLUT1Stimulates fatty acid and triglyceride synthesisInhibits I i poly sis and proteolysisShifts potassium ions from ECF to ICF', 'role': 'assistant'}]