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Tue Apr 20 11:00:08 EST 1993

weed-matthew at suned.zoo.cs.yale.edu replying to derekr at yang.earlham.edu 
> Such things as RNA's ability to catalyze its own replication,
> (something DNA can't do),

Let us be clear that you are discussing catalysis as dintinguished from
serving as a template.

> RNA's ability interact with amino(sp), acids directly,
> (something which I believe can't happen in DNA),

Certainly both RNA and DNA can and do interact with proteins.

The main difference between RNA and DNA is the presence of the 2-hydroxy group
in RNA.  It is chemically (and biochemically) simpler to synthesize ribose as
opposed to 2-deoxyribose.  Because of the 2-hydroxy groups, RNA is more
chemically reactive; that is both a boon and a bane.  While probably confers
more catalytic ability, it also introduces more chemical instability especially
under some assumed primitive earth conditions (dilute, slightly basic aqueous
solution).  In short, the RNA genome probably evolved first because it has
chemically easier and more catalytically versatile.  The DNA genome probably
evolved later from the RNA system because it had increased "genetic" stability.
                                 Dr. John S. Garavelli
                                 Database Coordinator
                                 Protein Information Resource
                                 National Biomedical Research Foundation
                                 Washington, DC  20007
                                 POSTMAST at GUNBRF.BITNET
                                 POSTMASTER at NBRF.GEORGETOWN.EDU

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