<prompt> The secondary structure of prion paicles is:Alfa helixBeta bendsBeta sheetsBeta turns  <response>: 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. 