A prion is best described as which of the following?

• A. an infectious DNA fragment
• B. an infectious protein lacking nucleic acids
• C. a small infectious RNA molecule
• D. a virus that infects bacteria

Answer: (B)

Verified step by step guidance

1. Step 1: Understand what a prion is by recalling its basic characteristics in microbiology. Prions are unique infectious agents that differ from viruses, bacteria, and other pathogens.
2. Step 2: Recognize that prions are composed solely of protein and do not contain nucleic acids (DNA or RNA), which distinguishes them from viruses, bacteria, and other infectious agents.
3. Step 3: Recall that prions cause disease by inducing abnormal folding of normal cellular proteins, leading to neurodegenerative conditions.
4. Step 4: Compare the given options: an infectious DNA fragment, an infectious protein lacking nucleic acids, a small infectious RNA molecule, and a virus that infects bacteria (bacteriophage).
5. Step 5: Conclude that the correct description of a prion is 'an infectious protein lacking nucleic acids' because it matches the unique nature of prions as proteinaceous infectious particles without genetic material.