Prions are composed largely of

Options

A. ssRNA
B. Prp-protein
C. ssDNA
D. Prp-lipoprotem

Answer

### Step-by-Step Solution:

1. **Understanding Prions**: Prions are infectious agents that are primarily composed of protein. They are known to cause neurodegenerative diseases by inducing abnormal folding of normal cellular proteins in the brain.

2. **Identifying the Composition**: The question asks what prions are largely composed of. The options provided are:
- Option 1: Single-stranded RNA
- Option 2: PRP protein
- Option 3: Single-stranded DNA
- Option 4: PRP lipoprotein

3. **Analyzing the Options**:
- **Single-stranded RNA**: This is not correct as prions do not contain nucleic acids like RNA or DNA.
- **PRP protein**: This is correct. Prions are primarily composed of a misfolded form of the prion protein (PRP).
- **Single-stranded DNA**: This is also incorrect for the same reason as RNA; prions do not contain DNA.
- **PRP lipoprotein**: While PRP is a protein, it is not classified as a lipoprotein. Therefore, this option is incorrect.

4. **Conclusion**: Based on the analysis, prions are largely composed of PRP protein. Thus, the correct answer is **Option 2: PRP protein**.