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From: emigh@ecsvax.UUCP
Newsgroups: sci.bio
Subject: Re: question
Message-ID: <2840@ecsvax.UUCP>
Date: Mon, 30-Mar-87 13:27:50 EST
Article-I.D.: ecsvax.2840
Posted: Mon Mar 30 13:27:50 1987
Date-Received: Wed, 1-Apr-87 01:15:29 EST
References: <11189@teknowledge-vaxc.ARPA> <978@aecom.UUCP> <3310@udenva.UUCP>
Reply-To: emigh@ecsvax.UUCP (Ted Emigh)
Organization: UNC Educational Computing Service
Lines: 35


In article <3310@udenva.UUCP> agranok@udenva.UUCP (Alexander Granok) writes:
>(Craig Werner) writes:
>>(Randy Burns) writes:
>>> I was wondering roughly how many 'bytes' of information are contained
>>> within human chromosomes?

>>	Hence, if a byte is a base pair, that's your answer, although
>>only two bits are required to specify a base, ergo a 'byte' could 
>>actually be a tetranucleotide, but most sequences are stored as
>>letters (ATCG). 

>The whole arguement gets caught up in definitions, here.  I would consider a
>bit to be a base pair, and a byte to be the set of three that encodes for one
>amino acid.  Instead of eight bits to a byte, there are three.  After all, one
>base pair by itself doesn't do much good.  But, if a base pair is a bit, then

In the same way, a byte doesn't do much good in floating point arithmetic.:-)
The problem, of course, is that not all the genome is used for the message
in polypeptide chains.  There are noncoding regions (particularly in
eukaryotic organisms); rRNAs (often many thousand copies of each gene); tRNAs
(again with lots of copies except in the  prokaryotes and organelles); etc.
In humans, it is estimated that only 1-2% of all the DNA actually encodes
for amino acids.
This is mostly a problem of semantics.  If we wish to use "byte" as the
smallest unit of meaningful information, then the nucleotide is the byte.
The addition of the complementary base (to make a base pair) adds no additional
information, so the base pair could be considered as the "byte" as well.


-- 
Ted H. Emigh     Genetics and Statistics, North Carolina State U, Raleigh  NC
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