Bart_Corsaro_at_USLRMG01 at internetmail.pr.cyanamid.com
> Subject: Re[2]: virus debate-help needed
> Steve wrote
> >My reflection on that is that while viruses do "reproduce" thus
...
> I would disagree that viruses do not "excrete" (i.e. form waste
...
> ATP. So from your own definition I would consider viruses living
but very
> parasitic organisms.
I agree with Bart - viruses are the ultimate parasites, given that
they do not require their own machinery for metabolism, but pirate
other cells' machinery. Of course, they then run foul of the
things-with-legs and things-with-leaves school of reductionist
definitions of life, in that they do not excrete or display
irritability, do not grow, etc. However, I have been teaching my
undergraduate classes for the last 14 years (that long!! Aaaarrgh!)
that it is not whether viruses are living or dead in terms of
classical criteria that is the issue - it is the definition of life
itself that determines our perception of what is and what is not
alive. Devotees of the Web will have seen a discussion of this in
the tutorial I have put up at our site and on the Wisconsin server:
http://www.bocklabs.wsic.edu/ed/virtut1.htmlhttp://www.uct.ac.za/microbiology/virtut1.html
I maintain that life is the phenomenon that accompanies the
self-directed replication of nucleic acids - and that this can
manifest itself itself in a spectrum of backgrounds, from the
essentially inorganic milieu that is the niche occupied by
autotrophic bacteria to the cellular niche occupied by fastidious
bacteria and viruses. Worrying about whether viruses are living or
dead then becomes pointless.
_____________________________________________________
| Ed Rybicki, PhD | (ed at molbiol.uct.ac.za) |
| Dept Microbiology | University of Cape Town |
| Private Bag, Rondebosch | 7700, South Africa |
| fax: xx27-21-650 4023 | tel: xx27-21-650 3265 |
| URL: http://www.uct.ac.za/microbiology |
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