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From: emigh@ecsvax.UUCP
Newsgroups: sci.bio
Subject: Re: question
Message-ID: <2844@ecsvax.UUCP>
Date: Tue, 31-Mar-87 15:25:08 EST
Article-I.D.: ecsvax.2844
Posted: Tue Mar 31 15:25:08 1987
Date-Received: Thu, 2-Apr-87 03:46:35 EST
References: <2840@ecsvax.UUCP> <11189@teknowledge-vaxc.ARPA> <978@aecom.UUCP> <3310@udenva.UUCP> <2112@PUCC.PRINCETON.EDU>
Reply-To: emigh@ecsvax.UUCP (Ted Emigh)
Organization: NC State University
Lines: 42

In article <2112@PUCC.PRINCETON.EDU> 6065833@PUCC.PRINCETON.EDU writes:
>In article <2840@ecsvax.UUCP>, emigh@ecsvax.UUCP (Ted Emigh) writes, with
>regard to the information stored in genes:
> 
>>If we wish to use "byte" as the
>>smallest unit of meaningful information, then the nucleotide is the byte.
> 
>If you wish to regard the RNA's as the media for genetic storage, instead of
>DNA, fine.  This is an alternative theory ('DNA is just RNA's backup').  But co
>nsider that even if you discount duplicate pieces of RNA, there is the problem
>of huge pieces of RNA junk stuck on the ends which are cut off as the RNA
>strings leave the nucleus.  Not to mention that nonsense sequences in DNA
>are transcribed into RNA, and only later cut out.  How do you tell which
>nucleotides are meaningful?

I do not consider RNA as the media for genetic storage (except in the case
of RNA viruses).  RNA has two roles (and possibly more):  1) As an
intermediate step in going from DNA to polypeptide chains; and 2) as
molecules with enzymatic activity (rRNAs, tRNA, regulatory RNAs, etc).
I also do not feel that just because a segment of DNA will not make it
into a protein that it is "junk" -- only that we may not understand its
functions.  Obviously, 5' flanking regions have regulatory effects.  3'
flanking regions are involved in termination of transcription.  I am
unsure of the role of introns, but feel that they are not their by
chance.  They may serve as protection against endonucleases; or they may
be involved with nucleosome structure; or ....

But even with all of this (rRNAs, introns, flanking regions, ...), some
60% of the DNA in the human genome has **UNKNOWN** function (which doesn't
mean that it has no function).  Rather than trying to say that each
nucleotide MUST have some information, we should say that it is at the
nucleotide level that we have the potential for information.  As an
analogy, my old North Star Horizon CP/M computer effectively has 56K
memory.  I am positive that there are bytes among those 56K that have
NEVER contained ANY meaningful information -- but all 56K had the
potential for containing meaningful information.

-- 
Ted H. Emigh     Genetics and Statistics, North Carolina State U, Raleigh  NC
USENET: emigh@ecsvax.uucp		DOMAIN:	emigh%ecsvax.ncecs.edu
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