Re: OoL – out at first base?

On 9/12/2024 5:20 pm, erik simpson wrote:

On 12/8/24 9:54 PM, MarkE wrote:

We need prebiotic formation and supply of nucleotides for RNA world, and other models at some stage. The scope of the problem of the supply of these precursors is prone to underestimation.
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Nucleotides are chemically challenging in terms of the prebiotic synthesis and assembly of their three constituents of nitrogenous base, sugar and phosphate group.
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Harder again are the requirements for supply of these building blocks. You need (eventually) all canonical bases in sufficient concentration, purity, chirality, activation, distribution, location, etc.
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But the greatest problem I think is this: time. How long must you maintain the supply described above in order to assemble a self-replicating RNA strand? And even if you managed that, how much more time is needed before reaching a protocell capable of self-synthesising nucleotides? One million years? One hundred million years?
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A hypothised little warm pond with wetting/drying cycles (say) must provide a far-from-equilibrium system...for a million years...or hundreds of millions of years. You can’t pause the process, because any developing polymers will fall apart and reset the clock.
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What are the chances of that kind of geological and environmental stability and continuity?
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Therefore, the formation of an autonomous protocell naturalistically has vanishingly small probability.
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The LUCA (last universal common ancestor) lived about 200 My after the formation of the moon.  There's a very outside chance it lived of Mars. That would make the proximity of the moon's formation a little easier, but surviving the launch from Mars and months-long trip to earth isn't very likely.
 The first life probably in something like a "deep smoker" with lots clay available.  Clay is a fine surface to catalize organic compounds.
 

This makes the problem of time worse. If the first protocell capable of self-synthesising nucleotides developed this way, you need a "deep smoker" (or localised group) operating steadily for millions of years.
Also, you no longer have wetting and drying cycles, which seem indispensable to support concentration of reactants, polymerisation, etc.