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Evolutionary significance of RNA-containing enzymes

achabot at cat.ustanne.ns.ca achabot at cat.ustanne.ns.ca
Fri Oct 7 08:35:46 EST 1994

On 6 Oct 94 15:51:46, 
Dale R. Worley  <drw at taylor.mit.edu> wrote:

>According to the dogma du jour, the progenote (last common ancestor of
>all surviving living things) used DNA as its genetic material and
>proteins for most of its catalytic agents.  That suggests that all
>surviving RNA-containing catalytic agents have pre-progenote origins.
>In particular, the intron splicing systems seem to all involve
>ribozymes, thus suggesting that introns were present in the progenote.
>On the other hand, both the eubacteria and the achaeobacteria lack
>introns, whereas the eukaryotes have introns, which would suggest that
>introns arose only in the early ancestors of the eukaryotes.

That's news to me: the going theory, last time I checked, was the reverse: 
bacteria (both of the eu and the archaeo persuasion) _lost_ their introns 
during evolution: small packages do gain by being lean and mean.


>Does anybody have a fix on the current thinking in these areas?
>Dale Worley             Dept. of Math., MIT             drw at math.mit.edu
>If you ask an engineer, 'What is 3 times 4?' he does not answer at
>once.  He fishes a contraption known as a slide-rule out of his
>pocket, fiddles with it for a moment, and then says, 'Oh, about 12'.
>This may not impress you very much.  But if you say to him, 'What is
>371 times 422?' he will give you the answer to this in just about the
>same time, and without needing to write down any figures.
>-- W. W. Sawyer, "Mathematician's Delight"

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