Re: Scientific theory

>
>Test 1 (four nucleotides) would be meaningless unless DNA could function with different nucleotides than the known four.  But nobody knows this.  Given all the churning of genetic codes that must have gone on over the billions of years, it would be surprising if no instances of different nucleotides ever occurred.  If they haven't,  a likely implication is that DNA can't function with different nucleotides.  If so, DNA of all organisms would have the four nucleotides whether or not all organisms had a common origin.  
>

Mainly, the distances and steric effects (interference
of other atoms) that are very critical to having a
different nucleotide. In some respect the structures
are somewhat forgiving to degradation (inosine for
example), but this also affects transcription.

Where you actually see a pletora of non-Watson Crick
pairing is in single strand sequences such as you
might find with a DNA virus. Even more important
is single strand RNA where you have an enormous range
of possibilities for AA, AG, etc pairing.

I guess the fact that we have only the four DNA bases
would raise a small case for an RNA world, but anyway.
There are some differences in the universal codon table,
but they are few and very distant organisms.

I think a much stronger case can be made for the fact
that ribosomal RNA (rRNA) is virtually the same everywhere!
This is one of the real the core pieces of biomachinery.

But as I mentioned earlier, I think the problem has little
to do with what is true or false anymore, it is largely
a social/political problem now. It has not helped that
atheists have hijacked evolution and put a spin on it
that stokes the flames of Creationist reaction.

Wayne
Received on Fri Dec 10 07:43:10 2004