> Is a virus a living organism or a biological machine?
> Two Mechanical Engineers.
I don't think there's a definite answer to this: is a cell a biological
machine? There's also quite a large continuum of things that are
defined as viruses (obligate intracellular parasites with an eclipse
phase). My favourite virus (flu) has a relatively small genome with
only 10-11 genes and under the right circumstances it can limp along
without at least 4 of these. Quite simple diagrams can be drawn about
how the proteins encoded by these genes interact with each other to make
a new virus, as long as you're willing to ignore the host factors and
don't mind a degree of plausible guesswork. I've always thought of flu
as a piece of biological clockwork and have no problem with classifying
it as a non-living parasitic nanomachine. There are simpler viruses out
there too, even before you get down to the level of viroids and so on.
But, on the other hand, there are viruses with genomes that are orders
of magnitude larger than influenza's, including some that are comparable
in size to, if not larger than those of the smallest known free living
organisms. Where do you draw the line?
Probably not much help!
Paul (a virologist)