Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/18/84; site dartvax.UUCP
Path: utzoo!linus!decvax!dartvax!ericb
From: ericb@dartvax.UUCP (Eric J. Bivona)
Newsgroups: net.bio,net.origins,net.philosophy,net.sci,net.sf-lovers
Subject: Re: It doesn't take that much to self-reproduce
Message-ID: <2561@dartvax.UUCP>
Date: Mon, 12-Nov-84 21:35:26 EST
Article-I.D.: dartvax.2561
Posted: Mon Nov 12 21:35:26 1984
Date-Received: Tue, 13-Nov-84 06:56:48 EST
References: <241@hocsj.UUCP> <696@reed.UUCP>
Organization: Dartmouth College, Hanover, NH
Lines: 44

> 
> > That was my thinking up to this morning.  Now it strikes me that I have
> > been glossing over a pretty complex step, one which is likely to have a
> > lower probability than either of the ones mentioned above.  That is the
> > step of going from something that is merely alive to a self-reproducing
> > (SR) cell.  This, it seems to me, is the biggest step of the three.  It
> > is one thing for the amino acids to form something that in some abstract
> > sense is alive, it is quite another for this thing to be an SR organism.
> 
>    The improbable event in the origination of life seems to be the
> establishment of a functioning genetic code: The association of the DNA
> with certain proteins that it "codes for", and which can "read" the
> code, that is, produce the proteins coded for in the DNA.
> (The process of transcription is enzyme-dependent, and enzymes are coded
> for on the DNA).
> 
>    The improbable event is the origination of a self-maintaining
> DNA-protein system. That may sound like what you had in mind to begin
> with, but the production of molecules peculiar to an organism is a
> fundamental part of being (and staying) "alive". I don't think I begged
> the question.
> 
>                         Alexis Dimitriadis
>                           alexis@reed
> 
> 			  ...

The improbable event that Alexis mentions above is one of adding semantics
to a syntactic system.  This seems to me to be a *very* improbable event
because the mechanism for semantics (RNA transcription) is now coded for
in the DNA (excepting mitochondria).  In order to start at all, some original
standalone transcription system would have had to have been developed.  This
system (DNA & RNA transcription) would have existed in the cell without
benifiting the cell until some reasonable semantic code was arrived at.

This is where I would bet Nature spent three of the last four billion
years [overdue and overbudget!?! :-) ]

-- 
Eric Bivona
"Once a gene sequence, always a gene sequence"
UUCP:   ...!{astrovax, cornell, decvax, linus}!dartvax!ericb
CSNET:  ericb@dartmouth
ARPA:   ericb%dartmouth@csnet-relay