Question

Radiation is a frequent method of sterilization. It is effective because it causes damage to DNA. However, prions, the agents that cause diseases such as mad cow disease, are unaffected by these treatments because they lack DNA. What is the definition of a prion?
Prions are small carbohydrate molecules that do not encode DNA. Prions are proteins folded into the correct configuration. Prions are proteins that are folded incorrectly. Prions are small RNA molecules that do not encode proteins.

Answer 1

The correct answer is: Prions are proteins that are folded incorrectly.

These misfolded proteins have abnormal 3D structure but the cause is not clearly known. They aggregate in tissue and cause it damage and cell death. Prion aggregates are stable, meaning that are resistant to denaturation by chemical and physical agents.  

Prions cause neurodegenerative diseases such as Creutzfeldt–Jakob disease (fatal degenerative brain disorder) or Gerstmann–Sträussler–Scheinker syndrome (also fatal).