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Bacteria and viruses

Mike O'Hara mohara at ihug.co.nz
Wed Sep 11 23:12:01 EST 1996


re: posts on 'are viruses alive'

I also think Ed Rybicki gave a reasoned answer and to a certain extent, 
complexity and/or life  is in the eye of the beholder.

some of the  work on models for early evolution has involved the use of 
very small bacteriophage such as Q-beta. The interesting thing about 
this sequence of nucleic acids is that it can effectively evolve - 
during the replication process there are sometimes mistakes made in the 
replicated sequence. 

The environment of the experiment (read: model of primitive earth) is 
such that all of the molecules, 'parents' and 'off-spring',  compete for 
free nucleotides to replicate. If one of the mutant sequences happens to 
have higher affinity for the nucleotides that the original and any other 
off-spring, it will come to dominate the sequence population. Until it 
in turn is supplanted. 

The long-winded point  I am trying to make is that this relatively 
'complex' behaviour is basically chemistry, ie. the higher the 
nucleotide affinities and/or the better the template the faster the 
replication the greater the number of copies. By the definition Ed 
Rybicki posted (nice definition by the way), the individual sequence may 
not be alive, but the system is...

Mike O'Hara, Ph.D.



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