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I think the fundamental problem is that a strand of PNA floating in water is just a strand of PNA floating in water. It isn't an organism, because organisms do

I think the fundamental problem is that a strand of PNA floating in water is just a strand of PNA floating in water. It isn't an organism, because organisms do things, things that require inputs of energy. I don't see how this lonely strand of PNA ever figures out how to spontaneously give itself a metabolism. Without having a metabolism to begin with, that PNA strand will never do anything.

hwillis 9y ago
The metabolism is to simply wait for resources to react naturally. PNA in sufficient concentrations and conditions will continue to polymerize and grow just by random chance. It's not any different from what happens inside a simple cell, really: ATP and other resources are for the most part just present inside the cell. It's just that for life to come about those conditions or something like them have to exist naturally. As the RNA/pre-RNA chain grows, there will be natural selection for any sequences that catalyze polymerization. This will eventually either lead to self-catalyzing replication or a mutual replication. AFAIK the second one is considered more likely because although RNA can self-catalyze it's not very good at it (of course, it doesn't really need to be). Mutual replication would require a primitive polymerase being spontaneously generated, which would allow an RNA-like molecule to -self-replicate. Eventually an chain would be created that could replicate via copies of itself, and that molecule would be able to spread beyond the original catalyzing molecule and outcompete anything else (since it would be able to replicate with any copies it made, it would grow exponentially rather than linearly).
- mtdewcmu 9y ago
  My proposal is basically that the proto-organism has to learn to eat before it can do anything else. The processes that you have described could still have important roles to play.

hwillis 9y ago

The metabolism is to simply wait for resources to react naturally. PNA in sufficient concentrations and conditions will continue to polymerize and grow just by random chance. It's not any different from what happens inside a simple cell, really: ATP and other resources are for the most part just present inside the cell. It's just that for life to come about those conditions or something like them have to exist naturally. As the RNA/pre-RNA chain grows, there will be natural selection for any sequences that catalyze polymerization. This will eventually either lead to self-catalyzing replication or a mutual replication. AFAIK the second one is considered more likely because although RNA can self-catalyze it's not very good at it (of course, it doesn't really need to be). Mutual replication would require a primitive polymerase being spontaneously generated, which would allow an RNA-like molecule to -self-replicate. Eventually an chain would be created that could replicate via copies of itself, and that molecule would be able to spread beyond the original catalyzing molecule and outcompete anything else (since it would be able to replicate with any copies it made, it would grow exponentially rather than linearly).

mtdewcmu 9y ago
My proposal is basically that the proto-organism has to learn to eat before it can do anything else. The processes that you have described could still have important roles to play.