| | Re: Do All Living Organisms Have DNA?
Well, citing my virology profesor I say that viruses are more like "biological entities", since there's not a definition of living being that applies to them up to now, not completely at least, that's the reason of the controversy.
There's a theory of the existence of a primitive RNA world, in which the nucleic acid of organisms (bacteria) was RNA.
According to this theory, viruses evolved and created DNA as a way to avoid bacterial endonucleases (then RNA specific), in other words, to fit for survival. These viruses introduced DNA in the RNA bearing bacteria and eventually DNA took over RNA as a more effective way to store and manage information.
I don't have the reference with me right now (my computer is on repair), but I'll post it as soon as I recover it.
By the way Bonnie, what you say applies for a few virus families (i.e. retrovirus). Most RNA viruses have RNA dependent RNA polymerases, which means they can have their RNA replicate directly from a RNA template, completely without DNA.