From: William Benzon (email@example.com)
Date: Wed 09 Jul 2003 - 15:21:03 GMT
You've posted the following observation to the list several times. It
didn't make sense the first time I saw it and it hasn't improved any through
repetition. I've asked Tim Perper to comment on it, as he's a biologist
(genetics) by training. Then I offer a comment of two.
* * * *
on 7/9/03 1:34 AM, Keith Henson at firstname.lastname@example.org wrote:
> Consider the example of a listing on paper of the base pairs of a gene, say
> hemoglobin. Would the listing have an apologetic disclaimer on it that
> this listing was only a *listing* of hemoglobin and not the real gene? No
> way! The list *is* the gene.
> Because you can type in or scan the list and feed the information to a gene
> synthesizer, get the DNA out, stick it in a cell and away it goes making
> the hemoglobin protein. I.e., a gene is a particular sequence of
> information. Now to get the gene to make protein (or regulate another gene
> or some other function) it has to be encoded in DNA and inside a cell.
Bill Benzon forwarded to me Keith Henson's posting to the effect that a
list of bases on paper "is" the gene. The answer is No, it is not.
The first reason is that biologists -- my field of training; in fact, I
was trained as a geneticist -- understand genes as parts of cells and
organisms, in which they have certain functions. One is expression,
another is replication. If, for example, a base sequence in DNA is
expressed under certain cellular conditions as an amino acid sequence,
then the gene in question can be defined, in part, by its expression.
But a list of bases on paper does not express itself in the
geneticist's and biologist's sense, and no cellular mechanism exists
that could express that sequence. Real sequences of real bases are
expressed in real cells; lists typed on paper are not. So the list on
paper has neither expressive function nor capability, and is therefore
not a gene.
One can waffle this point by saying that a biochemist in a laboratory
can read the typed sequence of bases and can then prepare an amino acid
sequence that corresponds to it. Of course -- and the possibility is
trivial. When geneticists talk about gene expression, we do not mean
biochemists in laboratories; we mean activities of cells. So this way
waffle the point is just silly.
Second, the list of bases on paper does not and cannot replicate itself
in the manner of double-helical, enzymatic replication of genes in
cells or in in vitro systems. One cannot waffle this point either, for
example, by saying that we human beings can replicate the list by
xeroxing it. In cells, genes replicate themselves with the aid of
cellular mechanisms. Lists of bases on paper do not replicate
themselves, and therefore lack one of the crucial defining
characteristics of genes -- that of self-replication.
A stronger case can be made -- and has been made -- for an "artificial
life" (AL) approach, in which a list of symbols in computer memory is
"replicated" as part of the function of a computer program. But Henson seems not to be making an AL-type claim.
Because a list of bases on paper lacks two crucial features of real
genes -- expression and self-replication -- Henson's argument appears
to be invalid.
* * * * * *
It seems to me that if the gene were Just Information, then the encoding
medium should be irrelevant. If someone has a hemoglobin deficiency, we
could treat it by just folding up the paper list for the hemoglobin gene;
have them swallow it; and they should be producing hemoglobin in a short
time. Or make a tinker-toy model of the sequence of base pairs and have
them sleep with it so they model can impart the information to their body.
Obviously, the "encoding" medium is critical, it is not the throwaway that
the "information only" position requires it to be. Still, if you really want
to maintain that position, then why not generalize it?
We could, for example, argue that an automobile is just information. You
take the plans for the automobile -- which, these days, are created in
electronic form -- feed them into an automobile synthesizer (aka a factory)
and before you know it the thing is cranking out automobiles. The principle
is the same:
information + synthesizer = The Real Thing
I don't think so.
-- William L. Benzon 708 Jersey Avenue, Apt. 2A Jersey City, NJ 07302 201 217-1010 "You won't get a wild heroic ride to heaven on pretty little sounds."--George Ives Mind-Culture Coevolution: http://asweknowit.ca/evcult/ =============================================================== This was distributed via the memetics list associated with the Journal of Memetics - Evolutionary Models of Information Transmission For information about the journal and the list (e.g. unsubscribing) see: http://www.cpm.mmu.ac.uk/jom-emit
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