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From: cherry@husc4.UUCP
Newsgroups: sci.bio
Subject: Re: question - DNA's information
Message-ID: <1534@husc6.UUCP>
Date: Mon, 30-Mar-87 23:46:38 EST
Article-I.D.: husc6.1534
Posted: Mon Mar 30 23:46:38 1987
Date-Received: Wed, 1-Apr-87 03:33:39 EST
References: <11189@teknowledge-vaxc.ARPA> <978@aecom.UUCP> <3310@udenva.UUCP>
Sender: news@husc6.UUCP
Reply-To: cherry%frodo.decnet@mghccc.harvard.edu (Mike Cherry)
Organization: Dept. of Molecular Biology, Mass. General Hosp.
Lines: 40

In article <3310@udenva.UUCP> agranok@udenva.UUCP (Alexander Granok) writes:
>In article <978@aecom.UUCP> werner@aecom.UUCP (Craig Werner) writes:
>>In article <11189@teknowledge-vaxc.ARPA>, rburns@teknowledge-vaxc.ARPA (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. 
>....   I guess it all depends on what you mean by "information."
>....   I think a better question might be something like:
>"How many amino acids (words in the language of proteins) are encoded for 
>on the human chromosomes?"  or "How many books could these words fill?
>....   Anyway, I think that would
>give a much more easily palpable idea for the enormity of information involved.


The unit of information stored in the chromosomes is the nucleotide. Not
all of that information ever makes it to proteins. Much of the information
in DNA never even makes it to RNA. Also there are many RNAs which either
have a structural or catalytic function encoded in the DNA. Thus the 
information is at the DNA level. 

Ciliates are single celled animals that have cilia for locomotion and two
types of nuclei. One called the micronucleus is where all the genetic
information is stored. The other nucleus called the macronucleus is where
all RNA synthesis occurs. The interesting fact is that in Oxytricha the 
macronucleus is made of only 15% of the micronuclear DNA complexity. 
Therefore 85% of this organism's inherited DNA sequences are not required 
to make the somatic nucleus where all RNA synthesis occurs, a neccesary 
precursor to protein synthesis.

Mike Cherry
Dept. of Molecular Biology, Mass. General Hospital, Boston
cherry%frodo.decnet@mghccc.harvard.edu