AP BIOLOGY

Detailed explanation-1: -With further work, it became apparent that prions were composed of a host-encoded protein, the prion protein (PrP), 2 which could exist in multiple conformational states: PrPC, the properly folded cellular isoform, and PrPSc, the misfolded and infectious isoform associated with prion disease (2).

Detailed explanation-2: -Prions, like all proteins, are composed of long chains of amino acids linked together. They exist in two forms. The first, PrPc, is found in abundance in nerve cells. Its exact function is unknown but it is thought to be innocuous.

Detailed explanation-3: -Prions are infectious agents that consist of protein, but no DNA or RNA, and seem to produce their deadly effects by duplicating their shapes and accumulating in tissues. They are thought to contribute to several progressive brain disorders, including mad cow disease and Creutzfeldt-Jakob disease.

Detailed explanation-4: -The cellular prion protein (PrPC) is a cell surface protein expressed in a variety of different organs and tissues with high expression levels in the central and peripheral nervous systems [1].

Detailed explanation-5: -Prions arise when normal proteins acquire an alternative conformation that becomes self-propagating. The most well-studied mammalian prions are composed of PrPSc proteins that cause Creutzfeldt-Jakob disease (CJD) in humans, scrapie in sheep, chronic wasting disease (CWD) in deer and elk, and mad cow disease.