Viruses, Viroids, Prions Flashcards
What is a Virus?
A sub-microscopic particle that consists of genetic material (DNA or RNA) contained within a protective protein coat called a capsid. They infect the cells of living organisms, but do not have a cellular structure and are unable to reproduce outside of a living system.
Are viruses living?
No.
Where was the first Virus discovered?
The Tobacco mosaic virus was found in a range of weed and crop species (tobacco, pepper, and tomato). It was found to damage leaves but does not kill plants.
What is the system to classify viruses based on?
- Types of hosts they infect
- Morphology (shape and structure)
- Type of Nucleic acid
- Mode of replication
What is a Viroid?
The infectious particle of plants. They do not have cellular structure, they depend upon enzymes of plant hosts for replication, they lack proteins, consist of a small RNA molecule (usually single stranded), and do not code for any proteins.
What are Prions?
More simple than viruses, they are proteins but lack hereditary material and do not have a cellular structure. Another infectious agent (BSE), non-living entities.
