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From: diaz@aecom.UUCP
Newsgroups: sci.bio
Subject: Re: information content of DNA
Message-ID: <1010@aecom.UUCP>
Date: Sat, 4-Apr-87 22:01:24 EST
Article-I.D.: aecom.1010
Posted: Sat Apr  4 22:01:24 1987
Date-Received: Wed, 8-Apr-87 03:31:18 EST
References: <2840@ecsvax.UUCP> <11189@teknowledge-vaxc.ARPA> <978@aecom.UUCP> <425@haddock.UUCP>
Organization: Graduate School of Hard Knocks
Lines: 27
Summary: On multiple reading frames in DNA

In article <425@haddock.UUCP>, johnc@haddock.UUCP (John Chambers) writes:
> One observation I haven't seen yet is the peculiarity of DNA called "reading
> frames"  This effectively triples the number of amino-acid sequences a given
> chunk of DNA encodes.  Multiply this by two for the complementary strand.
> 
> Granted, it is very rare that all six readings actually code for something
> in real life.  But this doesn't have much to do with the information content.
> 

Forget rare, there ain't no such animal. Although multiple reading
frames have been observed in phage, and transcription from complementary
strands observed in a variety of organisms (most recently, mice) there
is no documented example of anywhere near the six possible readings
coding for functional polypeptides. The implications for molecular
evolution for such a scheme would be disastrous. 

Organisms apparently think little about the advantages of compact
genomes, prokaryotes included. Rather there seems to be something about
having a lot of "junk" DNA that's beneficial, if I may be allowed this
ounce of teleology. Granted, we may one day realize that much satellite
and intron DNA may have functions we don't even dream about today, but I
truly doubt that coding for proteins will be one of them.

-- 
            dn/dx = Dan Diaz    (philabs!aecom!diaz)
            Department of Molecular Biology & Pizza Chemistry AECOM
            "Hold the E.coli"