Question

Are prions alive?

Answer 1

Hint: The word prion is derived from the term "protein-infectious particle." The hypothesized role of protein as an infectious agent is in contrast to all other known infectious agents, such as viruses, bacteria, fungi and parasites, all of which contain nucleic acids (DNA, RNA, or both).

Complete answer:
Prions are misfolded proteins capable of transmitting their misfolded shape to normal variants of the same protein. They characterize several fatal and communicable neurodegenerative diseases in humans and many other animals. It is not known what causes the normal protein to misfold, but the abnormal three-dimensional structure is suspected of conferring infectious properties and collapsing nearby protein molecules into the same shape.

Prion isoforms of prion protein (PrP), whose specific function is uncertain, are hypothesized to be the cause of transmissible spongiform encephalopathies (TSEs), including scrapie in sheep, chronic wasting disease (CWD) in deer, bovine spongiform encephalopathy (BSE) in cattle (commonly known as "mad cow disease") and, Creutzfeldt-Jakob disease (CJD) in humans. All known prion diseases in mammals affect the structure of the brain or other neural tissue; they are all progressive, have no known effective treatment and are always fatal.

Not only are prions not alive (and do not contain DNA), they can survive being boiled, treated with disinfectants, and can still infect other brains years after they have been transferred to a scalpel or other tool. Prions are not living organisms, however. Prions are infectious proteins. For unknown reasons, these proteins replicate abnormally and cause a domino effect in the surrounding proteins, which turn into stable structures.

Thus, prions are not alive.

Note: Prions form abnormal aggregates of proteins called amyloids, which accumulate in infected tissues and are associated with tissue damage and cell death. Amyloids are also responsible for several other neurodegenerative diseases such as Alzheimer's and Parkinson's.