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Re: Fw: Most popular/common dinosaur misconceptions
On 8/24/06, David Marjanovic <email@example.com> wrote:
> remember that most of proteome present in the mitochondria are of
> nuclear origin, which could imply a early gene transfer from
> mitochondria (or the original endossymbiont) to nucleus.
Certainly -- these must have happened before animal mitochondria started
evolving their own code.
Or maybe not. (Say, Ryckettsia has a non-standard genetic code.
Wolbachia has a non-standard code too - and there is registered gene
transfer to host.)
> How could genetic system with different genetic code be compatible?
> First, it could be the case that the translation system was not so
> specific or so reliable. Recall the wobble hypothesis of codon origin.
If the codes are too different, this still won't work.
Maybe they are not *too* different at that time - dozens of million of
years of previous coexhistence could have led to a high degree of
convergent coevolution and there is the stereochemical hypothesis for
the genetic code origin too.
> And, on the other hand, termination codon is not a yes or no codon,
> but a probabilistic codon - which depend somewhat of the genetic
> context (the flanking sequences).
Are you talking about selenocystein?
No, I'm refferring to the low efficiency oy Trp coding by UGA
(standard stop codon) in _Bacillus subtilis_ and in _Escherichia
Hatfield D, Diamond A. 1993 - UGA: a split personality in the
universal genetic code. Trends Genet. 9(3): 69-70