Which of the following is true about prions

Options

A. Useful polysaccharide of galactose
B. High molecular weight infectious proteins
C. Small nucleic acid fragments capable of replication
D. Low molecular weight infectious proteins.

Answer

### Step-by-Step Solution:

1. **Definition of Prions**:
- Prions are defined as proteinaceous infectious agents. They are essentially misfolded proteins that can induce other normal proteins to also misfold.

2. **Characteristics of Prions**:
- Prions are infectious because they can cause diseases by converting normal proteins into misfolded forms.
- They do not contain nucleic acids, which differentiates them from viruses and other infectious agents.

3. **Molecular Weight**:
- Prions have a low molecular weight compared to other infectious agents. This is an important characteristic that helps in identifying them.

4. **Evaluating the Options**:
- **Option A**: "Useful polysaccharides of galactose" - This is incorrect because prions do not contain polysaccharides.
- **Option B**: "High molecular weight of infectious protein" - This is also incorrect as prions are characterized by their low molecular weight.
- **Option C**: "A small nucleic acid fragment capable of replication" - This is incorrect because prions do not have nucleic acids at all.
- **Option D**: "Low molecular weight, infectious protein" - This is correct as it accurately describes prions.

5. **Conclusion**:
- The correct answer is **Option D: Low molecular weight, infectious protein**.