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From: johnc@haddock.UUCP
Newsgroups: sci.bio
Subject: Re: information content of DNA
Message-ID: <425@haddock.UUCP>
Date: Fri, 3-Apr-87 16:01:01 EST
Article-I.D.: haddock.425
Posted: Fri Apr  3 16:01:01 1987
Date-Received: Sun, 5-Apr-87 03:36:59 EST
References: <2840@ecsvax.UUCP> <11189@teknowledge-vaxc.ARPA> <978@aecom.UUCP> <2844@ecsvax.UUCP> <7659@ut-sally.UUCP>
Reply-To: johnc@haddock.ISC.COM.UUCP (John Chambers)
Organization: Interactive Systems, Boston
Lines: 34

>			 Consider a computer that on receiving
>a one-bit message will either print the Declaration of
>Independence or Hobbes' Leviathan. That one bit determines which
>is chosen, but does not fully describe either result. 

Red herring time.  The message contains exactly one bit.  The complexity
of the response has nothing whatsoever to do with the size of the message.
The original question was about the information content of human DNA, not
about the DNA's environment, which obviously contains much more information.

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.

I remember back in the early days of computing, a prof in a course held up
a punchcard with lots of holes in it, and another with no holes punched at
all, and asked the class to compare their information contents.  The correct
answer, of course, was that all the punchcards in the house contained exactly
the same amount of information: 12*80 bits.  Some of them contained all 0
bits, but that isn't less information than one with some holes punched out.

I wonder if anyone has ever built a computer with the possibility of multiple
"reading frames".  Consider an 8-bit memory, but a 16-bit instruction size.
If you start executing at address A and at A+1, you get two possibly very
different programs.  Can any real-life processors do this?  It happens
with DNA quite often.

-- 
	John Chambers	(617)247-1155
	...!ima!johnc	
[No, I don't work at cdx39 any more.]