Living virus?

Stefanie Greve S.Greve at tu-bs.de
Wed Sep 2 17:22:58 EST 1998


Hello, Sharon!

Chan H. Chong wrote:
> 
> Virus can reproduce itself only by infecting living cells.  What does this
> mean?  It is easy to think that virus is not live, since it needs cells to
> carryout reproduction, instead of reproducing on its own.  But what about
> parasites?  Do you suppose they can live without its host(s)?  

Can any organism live without its specific environmental conditions? A
cell as habitat is just another form of environment.

>Then why do we consider them as being live?  Because they metabolize?  Reproduce?  But
> if they don't have a host, they can't do either one of them.  What if a
> parasite looses its interest to find a host. 

That sounds to me like a suicidal parasite. :-)

> It will die even before having the chance to reproduce.  Only thing that differs is > the bio-make-up of the
> two:  Parasites are cellular, while viri are not.

What do you think might be an appropriate definition of life? The mere
existence of DNA or rather small Macromolecules as in Prions?

> But here is what everything comes down to.  Do you suppose all living things serve a purpose?

I do not think life needs a purpose. To me life is just a fact.
Admittedly fascinating.

> They live to reproduce.[..]
> Viri serves its purpose like any other life forms.
> They reproduce.  Not on its own, but they reproduce.  Again, like parasites,
> they need a living host.  Viri reproduce through living cells.  They need
> something live to reproduce, since it also is live.  For now, only living
> things can be reproduced through living things.  Non-living things cannot be
> reproduced through living things.  It won't even reproduce.  So, viri must
> also be live since it is reproduced through living things.  That makes clear
> sense to me, but if further questions arise, I'm welcome to meet them.  :)

What do mean to say? Viri "have themselves reproduced" by living cells?
Or are they just "reproduced" in living cells? Or do they reproduce
themselves? Could you please help me out with a definition of reproduce?
I thought it meant having offspring on one`s own.

Viri naturally need living cells to "become more viri", since without
the proper biochemical machinery and physicochemical surroundings this
is not possible. Obviously, viri do not have these without whole cells. 

What about plasmids or chloroplasts? Don`t they reproduce inside living
cells, but not outside? Now, are they lifeforms? 

I would appreciate enlightment!  :-]


Greetings

 Stefanie Greve



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