Question

Are viruses, viroids, and prions living?

Answer 1

Viruses:

1. They are infectious agents that replicate inside a host's body.
2. They are neither living nor non-living.
3. Examples- adenovirus, Hepatitis C virus, etc.
4. They usually lack a cell wall. Instead, they are surrounded by capsid (a protective protein coating)
5. They contain either RNA or DNA as the genetic material.
6. They utilize the hosts' machinery to replicate and transcribe their genome.

Viroids:

1. They are infectious agents that affect only plants (also known as plant viruses).
2. Structure- contains circular strands of RNA with no protein coating and are smaller than viruses.
3. Examples- potatoes, coconut palms, tomatoes, etc are affected by viroids.

Prions:

1. They are proteinaceous infectious particles, that have the potential to cause several neurodegenerative diseases in mammals.
2. Eg-Creutzfeldt Jakob disease.
3. They are non-living (unlike other pathogens).
4. Therefore, viruses, viroids, and prions do not have cells or even cell organelles which are paramount for life.
5. However, they also cannot be classified as “non-living” as they exhibit natural selection, a defining characteristic of life.