Prions are are made of proteins molecules only which is abnormally folded . Genetic material (DNA and RNA) is absent in prions.
They are infectious protein particles and can multiply themselves.
They have a molecular weight of about 35–36 kDa which is approximately same as virus.
Prions mainly affect the central nervous system and one of the best known is the scrapie agent of sheep and goat like animals which causes the animal to scrap itself against some objects.