IF the genetic code is basically just a
pyrimidine - hydrophobic/ 
purine - hydrophilic, split:

Then we may go further with the idea and these clues
for codons

1. Every base pair can work with two exception,
2 pyrimidines (U,C), or 2 purines (A,G).
U can bond with A or G
I (a modified form of A) can form with U,C, or A

2.  The code may well be based on amount of
pyrimidine or purine.
IF in 2nd position, UC/pyrimidine = phobic, 
GA/purine = philic

3. But if U in center position then C cannot be
on either side of that same strand or you have
the danger of dimers from UV. Thus no CUC
codon early on.

4, It would be doubtful to have U  in first position
when UAG, UGA, UAA all code for stop.
This suggest the U + a purine rule for stop.

5. Pyrimidine in 2nd position = phobic, but
if it is also in first, more phobic and 3rd 
most phobic

6. Purine in 2nd position = philic, but
if it is also in first, more philic, and 3rd
most philic.

7. The most easily made base in prebiotic
experments seems to be
in this order, purine A, purine G, pyrimidine
U, pyrimidine C. 
Note the prevalence of ATP

8. The initial fit in all 3 positions was probably not
the WC base pairing we're used to (A/U, G/C)
The fact that we have I as a replacement for A suggests
that A was first bound to U, and perhaps C and other A's

9. The U can base pair to the G in wobble position now.
It probably could or did in all 3 positions at the start.

10 When there is wobble in 3rd position it is always
either a purine (A or G) or a pyrimidine (U or C)
There can never be a wobble that offers one of each
in third position.

11 Stacking of 3 purines may be the most stable.
and perhaps best suit it for hydrophilic behavior.

12. Stacking of 3 pyrimidines may be the least
stable and perhaps best suit it for hydrophilic
behavior.

I contend that somehow these and other clues suggest
how first coding set up a philic/purine and 
phobic/pyrimidine coding system that evolved to the
code we have now.

Comment?
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