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From: mrh@cybvax0.UUCP (Mike Huybensz)
Newsgroups: net.origins
Subject: Re: The Central Dogma
Message-ID: <474@cybvax0.UUCP>
Date: Wed, 17-Apr-85 10:38:11 EST
Article-I.D.: cybvax0.474
Posted: Wed Apr 17 10:38:11 1985
Date-Received: Sat, 20-Apr-85 02:53:22 EST
References: <901@uwmacc.UUCP>
Reply-To: mrh@cybvax0.UUCP (Mike Huybensz)
Distribution: net
Organization: Cybermation, Inc., Cambridge, MA
Lines: 44

In article <901@uwmacc.UUCP> dubois@uwmacc.UUCP (Paul DuBois) writes:
> The Central Dogma is, in brief:  everything's genetic.  The proposition
> is that DNA is the sole repository of biological information and that
> the flow of such information is one-way, from the DNA to elsewhere
> (usually protein).  (This is probably an oversimplification; maybe
> Mike Huybensz or Stanley Friesen will comment.)

That's pretty much it.  DNA -> RNA -> protein.  There are some clear
exceptions to this pathway.  For example, it was dicovered that certain
viruses produce an RNA reverse transcriptase that does this:  RNA -> DNA.
Prions (such as Kuru) are thought to go: protein -> ? -> protein.  There
are probably more examples that I don't remember offhand.

Is it really a dogma?  The DNA -> RNA -> protein pathway was found, and
the hypothesis was made that because it was sufficient to explain
what we knew about life then, that was all.  It has since been found that
there are additional pathways.  This sort of procedure is a normal aspect
of science: make a hypothesis to provide direction to research, looking
for confirmations and exceptions to the hypothesis.  As more is learned,
the original hypothesis often represents what is known more and more
poorly.  Just as Newton's laws of motion are special cases under the
theory of relativity, so the "Central Dogma" is a special case (albeit the
most important one) under what we know today.

> My comment was directed to the idea that cultural transmission of
> information may provide a non-genetic way of propagating change, and
> in that way circumvents the Dogma.  I suppose the question then
> becomes, is all behavior genetic?  If it is, then of course the Dogma
> remains intact.

Transmission of parasites is also a non-genetic way of propagating change.
But that's besides the point.  There are non-genetic ways of propagating
change.  Formulating the "Central Dogma" theory was a method of requiring
explicit testing and identification of modes of propation of biological
information.

For a while, it was thought that learning or memory might be encoded in
DNA, RNA, or proteins.  It now seems to be encoded in synapses and
proteinaceous pathways within neurons.  The Central Dogma helped point
out the mechanisms that would be required for the former: when they
were looked for and not found, research shifted.
-- 

Mike Huybensz		...decvax!genrad!mit-eddie!cybvax0!mrh