Yes, I know GTP, UTP and so on also have important roles, but why did we, and so many other organisms evolve such that ATP is the universal source, important in energy conversions everywhere? Why adenosine?
I would flair this post as both biology and chemistry if I could.
In: Biology
If I remember right, ATP was the first of these that evolved. It’s the chicken and the egg here: Which came first, the chicken or the egg? The egg, obviously, because chickens didn’t exist until WAY after eggs did. If you’re going to say “Yes, but what about the chicken egg, then?” then you’re going to get a dozen chicken eggs thrown at your face; this isn’t philosophy.
Basically, ATP evolved SO LONG AGO that it’s just the energy transfer molecule. That’s it. It worked, it did its job and possibly even had an advantage at that purpose. As life evolves, it will hopefully favor efficiencies in certain areas, that things like signalling pathways and the energy cycle changed to be as efficient as possible with their respective molecules (or, at least, more efficient). ATP was already there, it worked, and by the time that GTP and UTP came along, it was the molecule for energy transfer. There wasn’t any reason to evolve a new one, especially one that wasn’t as good. And there were good reasons for different molecules for different purposes, as it reduces the risk of bad signals or other problems. There’s no competitive advantage to dividing purpose or redundancy, no scarcity of the specific elements that assemble the molecule, etc.
So life started, some life made this little molecule for energy purposes, and it was good enough at its job that it just became a general part of life. Then life evolved into complex organisms, and it was still there, doing its job the whole time. That’s it.
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