lpetrich
Contributor
Viruses have a lots of variety of genomes, much more than what cellular organisms do.
I'll be talking about the virions, the virus particles that spread outside of their host cells.
Their genomes can be linear or circular, DNA or RNA, single-stranded or double-stranded, with the single-stranded ones having either positive or negative "sense". Some RNA viruses are copied onto DNA as part of their replication, making them "retroviruses".
Sense (molecular biology) - RNA has positive sense if it can be directly used as messenger RNA to make the target protein, and negative sense if one has to make a copy of it for that. DNA has positive sense if RNA copied from it can be directly used as messenger RNA, and negative sense if either the DNA or the RNA has to be copied for that.
This is related to the question of the origin of viruses. There are three main theories, theories that are not mutually exclusive, and theories that may involve multiple origin events.
I'll be talking about the virions, the virus particles that spread outside of their host cells.
Their genomes can be linear or circular, DNA or RNA, single-stranded or double-stranded, with the single-stranded ones having either positive or negative "sense". Some RNA viruses are copied onto DNA as part of their replication, making them "retroviruses".
Sense (molecular biology) - RNA has positive sense if it can be directly used as messenger RNA to make the target protein, and negative sense if one has to make a copy of it for that. DNA has positive sense if RNA copied from it can be directly used as messenger RNA, and negative sense if either the DNA or the RNA has to be copied for that.
This is related to the question of the origin of viruses. There are three main theories, theories that are not mutually exclusive, and theories that may involve multiple origin events.
- Primordial organism
- Degenerate cellular organism
- Escaped transposable element in the genome (transposon)