This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': 'The secondary structure of prion paicles is: \nSelect and explain. \nA. Alfa helix, B. Beta bends, C. Beta sheets, D. Beta turns', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C i.e. Betasheets There is no difference in amino acid & gene sequence, primary structure & post translational modifications between normal cellular isoform of non infectious (host) prion protein (PrPC) and infectious (pathological) prion proteins (PrPsc). The key to becoming infectious lies in 3 dimensional conformation i.e. a number of a -helices present in non infectious PrPC are replaced by /3 sheets in infectious (PrPse) formQ.', 'role': 'assistant'}]