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tRNA evolution



More and more I think the major clue to the origin of life
lies in tRNA. I was thinking last night about how it could
first start and came up with this scenario.

We start with a single strand of nucleotides. 
It has folds caused by the order of nucleotides, h-bonding
and other forces.

The folds are bordered on both ends by unfolded stretches.

Thus we have a folded portion with acceptor like stems on
both ends.

Through chemical selection the fold became more precise,
and at some point one of the acceptor stems folded over on
itself to make the anticodon loop. Thus leaving the other
end as our present day acceptor stem.

All of this makes sense, fits the basic facts, and is easy to visualize.

But that raises more questions:
1.  Why was a folded proto tRNA selected  that is that
size and shape?
2. Why was a folded proto tRNA selected that size and shape with
two single strand proto-acceptor stems on each end.
3. Why are the two ends pointing in the same direction?
3. What did those two acceptor strands - h-bond to
(if it was an h-bond)?
4. Why are the two proto acceptor strands 76 a apart?
What does that fit?
5. Why would connecting both ends to another molecule (s)
help this one better survive its environment.
6. Somehow the proto tRNA  attaching to peptide bonds 
was an advantage -
how did it do it? Why did it do it?

I firmly believe some biochemist out there sees the missing
fact - sees some connection between the tRNA ends and the peptide
bond that the tRNA exactly fits. And they've probably said
something like, 'that's curious". If you are he - and you see
the reason proto tRNA in the shape it is, is best adapted to
symbiotic behavior with a peptide bonds - let me know!

Tom Hendricks






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