Protein chains are used by all living cells to manufacture the molecules we're made of. They arrange soure material into new molecules. Many proteins are intend

Protein chains are used by all living cells to manufacture the molecules we're made of. They arrange soure material into new molecules. Many proteins are intended to manufacture themselves. This capability is usually tightly regulated by availability of the source materials within cells. Prions are proteins too. And they can create themselves from source material too. But their source material are proteins which are not intended for processing. As such, prions are defined like weeds in a garden: They're not supposed to be there. Marvel at the wonderful world that is biology: https://en.wikipedia.org/wiki/Protein https://en.wikipedia.org/wiki/Protein