This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Glycogen Metabolism and Glycogen Storage, Subject name: Biochemistry
[{'content': 'Which of the following enzyme is absent in muscle? \nSelect and explain. \nA. Glucose-1-phosphatase, B. Glucose 6 phosphatase, C. Glycogen phosphorylase, D. Thiophorase', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ref: Harper's Illustrated Biochemistry, 27th edition and Lippincott !s Biochemistry, 3rd editionExplanation:FATE OF MUSCLE GLYCOGENIn muscle, enzyme Glucose - 6- phosphatase is absent.This enzyme catalyzes the final step of glycogenolysis.Hence muscle glycogenolysis does not contribute to blood glucose directly.Glycogen of muscle can only be converted upto glucose - 6 - phosphate as muscle lacks glucose - 6 - phosphatase.Glucose - 6 - phosphate cannot cross the plasma membrane and enters the glycolytic cycle, where it is converted into lactic acid.This lactic acid cross the plasma membrane and reaches liver to form glucose", 'role': 'assistant'}]