What is a prion best described as?

A prion is best described as a protein, specifically a misfolded form of a normal protein that can induce other proteins to also misfold. This unique property is what distinguishes prions from other biological entities. Unlike viruses, which contain genetic material (either DNA or RNA) and require a host cell to replicate, prions propagate through protein-to-protein interactions without any nucleic acid involved. Their ability to cause diseases such as Creutzfeldt-Jakob disease and Mad Cow disease is attributed to the aggregation of these misfolded proteins, leading to neurodegeneration.

In contrast, bacteria and other prokaryotes are cellular organisms, whereas transposons are segments of DNA that can move within the genome but do not represent a separate infectious agent like prions. The defining characteristic of prions is their nature as aberrant proteins, making them distinct in the spectrum of biological entities involved in disease.