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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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