Newsgroups: comp.ai.genetic
From: stevem@comtch.iea.com (Steve McGrew)
Subject: Re: how many genes do we have?
Organization: New Light Industries, Ltd.
References: <5bdbtd$b9c@news.knoware.nl> <5bdrva$qna@mercury.hgmp.mrc.ac.uk> <32DBB1BD.57E8@his.com>
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In article <32DBB1BD.57E8@his.com>, gary@his.com wrote:
>60,000 - That's remarkable in its brevity. I suppose counting the 
>mitochondrial DNA doesn't add much more (if it is not already counted). 
>Think of a protein as a computational unit, akin to a line of code 
>(whatever high level language you wish), then think of all the software 
>out there (some of it mine) consisting of hundreds of thousands of lines 
>of code and having the intelligence of a fence post. Seems like 
>something else must be operating here.

        There *is* something else operating here.   A lot of something elses.  
To begin with, the arrangement of the genes is important.  Genes are located 
in "operons", which have control regions that control the rate at which the 
genes contained in the operon will be expressed.  Various substances either 
promote or inhibit the action of the operon.  Those substances include 
metabolic products, environmental substances, and the products of genes.

        The unfertilized egg is far more than a homogeneous blob containing  
some DNA.  It is a highly structured system, and the structure appears to be 
partitioned assymmetrically after fertilization among the daughter cells as 
the embryo develops.  So, there is almost certainly a fair amount of 
information in the egg's structure, independent of the DNA, that helps control 
embryonic development and the ultimate structure of the mature organism.

        Finally, it is a vast oversimplification to represent that the DNA 
contains the information of "only" 60,000 or so genes.  A gene gets translated 
into a protein, which is a complex active system in its own right.  A gene can 
be a sequence of hundreds or thousands of nucleotides, resulting in proteins 
with hundreds or thousands of amino acids.  Variation in a single amino acid 
can have a measurable-- and sometimes profound--effect on the function of the 
protein.  To say that a human being contains 60,000 genes is akin to saying 
that the Internet is composed primarily of 30 or 40 kinds of computers: it 
ignores the number of copies of computers, interrelations between the 
computers,  the huge number of different kinds of software on the individual 
computers, and which computers are turned on.

        Steve

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