> Continuing discussion with of Mario Vaneechoutte:
>
> >> >> Genes use cell machinery for self-replication in the same way as
> >> >> viruses do. Or may be you don't consider viruses replicators?
> >> >
> >> >Viruses can only exist because there are cells. They are replicated by
> >> >cells.
> >>
> >> But viruses have their own goals and meanings; in this sense they are
> >> autonomous and alive. If you think that viruses are not replicators,
> >> then all parasitic organisms are also not replicators because they
> >> require a living host to live in. They can not replicate themselves
> >> without a host. Do you accept this? May be you consider replicators
> >> only autotrophic organisms?
> >
> >The difference is that viruses are informational parasites. The replication
of
> >their genome has to be done by other organisms. Other parasites have their
own
> >replication machinery, and depend on hosts for metabolic reasons only. Just
> >like any organism (except a few bacterial species) relies on others for its
> >metabolism. After all, predation (eating other organisms) is an extreme form
of
> >parasitism.
>
> Mario, you have not answered my question. I don't mind if you can call viruses
> informational parasites. The questions are: are they replicators and
> are they alive?
They are not replicators: they depend on the gene replication machinery of other
organisms for the replication of their genes.Other parasites do not. Other
parasites
depend only for metabolism on other organisms, having their own replication
machinery.
Are they alive? They do not have metabolism, so what?
Am I alive? I have metabolic funtions, so what?
I am part of a 4 billion year old organism which is a trillion, trillion, ...
billion cells large. Isolate me (or any other 'living organism' or a virus) from
the
rest of this organism and processes in my body (or the replication of the virus)
will soon stop. You can not answer the question of what life is by studying a
single
living organism. Life as we now it is the metabolic network formed by all the
descendants of that first cell. I think that when you can explain the origin of
the
first cell, that the rest of the explanations follows.
Viruses are part of the organism Life, but asking whether they are alive is the
wrong kind of question I believe, just the same as asking whether I am alive.
>
>
> There are many other cases when host-parasite relationships
> involve interpretation of signs. For example, some insect parasitoids
> release host hormones which are interpreted by the host. Without
> this interpretation parasitism will not be successful and there
> will be no self-reproduction of the parasite.
OK. But this kind of interaction happens not only between host and parasite, it
happens continuously between all kinds of organisms. We influence each others
metabolism all of the time. I do not see the relevance.
Mario