Thinking out loud

Thinking out loud about the genetic code:

1. I note that most wobbles are purines I, Inosinic acid has
a purine base and can pair with U,A, or C G, a purine can
pair with U, C U, a pyrimidine can pair with either
purine A or G (this supports the general rule of a mostly
purine world before the code was perfected)

2. Why 3 bases in a codon? It may be a result of dimer
damage. With 3 you can divide the pyrimidines. Thus
either purine,pyrimidine, purine or pyrimidine, purine,
pyrimidine, would be safe from dimers as either a codon
or anticodon. No other 3 position configuration would be
free of possible dimer damage. The rest would have some
dimer danger on one or the other side - either the
anticodon, or the codon side.

3. The code may have begun as hydrophilic in this loose
general way
a. mostly water - so water chemistry would be favored

b. mostly purine bases , A/G, in prebiotic experiments

c. dimers , 2 pyrimidines together on the same strand
next to each other, would be eliminated from coding by
UV damage in both the anti- codon position or the
codon position.

d. dimer damage leaves us with only 2 codons that are free
of two pyrimidines in a row purine,pyrimidine, purine (or
its opposite) pyrimidine, purine, pyrimidine. BUT

e. wobble pairing with purines would give purines another
edge - many more ways to code purine in center position.

f. the only pyrimidine 2nd position that would work is the
single - purine, pyrimidine,purine codon.

g. at the acceptor stem there may be either a hydrophilic or
hydrophobic amino acid. But only the hydrophilic would
work at first due to its reaction in water.

Thus the code would have a slight edge for purines on the
anticodon loop AND a slight edge for hydrophilic amino acids
on the acceptor stem end.

Comment?

Now things seem to be moving fast.

Thus it would seem that because of dimers and their limit to
how a codon could be set up, there would be a preponderonce
of purines in coding, and hydrophilic amino acids at the
other end.