Prion diseases involve conversion of the normal cellular prion protein (PrPC) into the scrapie form (PrPSc). The fundamental structural difference between these two conformers is that PrPSc is:

• A Rich in alpha helix and protease sensitive
• B Rich in beta sheet, protease resistant, and capable of templating further conversion of PrPC ✓
• C Unfolded and randomly coiled, explaining its aggregation
• D Covalently cross-linked by disulfide bonds between different molecules

Explanation

PrPC is predominantly alpha-helical and protease sensitive, whereas PrPSc is rich in beta sheet, aggregates into amyloid fibrils, resists protease digestion, and acts as a template recruiting PrPC into the pathogenic conformation. This propagates disease without any nucleic acid. Option A describes PrPC itself. PrPSc is highly ordered, not randomly coiled, and its propagation relies on non-covalent templating rather than intermolecular disulfide cross-links.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.