Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site allegra.UUCP Path: utzoo!watmath!clyde!burl!ulysses!allegra!jdd From: jdd@allegra.UUCP (John DeTreville) Newsgroups: net.bio Subject: Re: Genetic Information: Chromosomes vs. DNA Message-ID: <2698@allegra.UUCP> Date: Tue, 14-Aug-84 13:07:36 EDT Article-I.D.: allegra.2698 Posted: Tue Aug 14 13:07:36 1984 Date-Received: Wed, 15-Aug-84 01:40:37 EDT Organization: AT&T Bell Laboratories, Murray Hill Lines: 30 Thanks for the many replies on my recent query about the relation between chromosomes and DNA (and thank everyone for \not/ just posting it!). I received replies from (in alphabetical order) Mark Biggar, Matt Crawford, Richard Goldschmidt, Les Gondor, Berry Kercheval, Stan King, Pat Parseghian, Donn Seeley and Robert Thau. The low-level answer is "Simple. Chromosomes are composed of DNA." ("Like beer comes in six-packs, and beer comes in cans.") The medium-level answer is "The chromosome is the DNA plus some proteins (histones) to give it some structure. Leaving a long molecule loose would increase the chances of it becoming tangled or broken, so the histones act as spools upon which the DNA is wound." The high-level answer is that "chromosomes are structures of protein around which are wound tangled strings of DNA. You get several levels of structure, starting with the famous double helix (a double strand of DNA wound up like a telephone cord), then helices of helices all the way up to peculiarly shaped knobs and then finally the macroscopic (but still microscopic) X-shape that you see with optical microscopes. The funny configuration is laid out so that various stretches of DNA ('genes') can easily be turned off or on for the purpose of copying off pieces which store useful information such as protein templates. I seem to remember a nice, layman-oriented article on DNA structure in Scientific American a few years back." Cheers, John ("Now That I Know This, What Can I Use It For?") DeTreville Ball Labs, Murray Hill