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"