One of the popular theories about the origin of life on earth is the “RNA world”. To simplistically sum it up for the layman, RNA molecules arose by chance in the primordial soup that could catalylize simple biochemical reactions (such as/and) replicating themselves/catalysing simple reactions.
From there (following the central dogma) RNA can go forward to make some enzymatic proteins, and go back to encode DNA. Bottom line is that RNA molecules encoded for proteins that had better enzymatic function and “went back” to DNA that could store genetic info better.
I think there was a RNA world. But after surfing some sites on the Net, the question of whether RNA had a long enough time to evolve to explain the first cells.
I’m just looking for feedback. A big arguement against the RNA World is that CELLUAR life is found in the fossil record almost (Geological time scales)immediatedly after the permissable temperature time period.
The Earth cools and one celled organisms are there. As soon as we can find them; according to the fossil record (and I don’t know this).
This is where I’m unqualified.
But, from what I’ve gathered–The statistical propability of of self cataytic RNA doing it’s thing would take like 900 million years.
Again, maybe I’m off, but cells arose early in Earth’s fossil record.
My stats may be way off (this is from a quick web search), but how does RNA start all of life on this planet?
The steps from RNA to full fledged cells do seem to have happened rather quickly, which is why many of us biochemist types think that J.B.S. Haldanes “interstellar spore” ideas might have some validity.
Im not sure how helpful this will be, but according to This article, life formed withing several hundred years after the formation of the planet. But who is to say that all that chaos and upheaval didn’t speed up the process? (compared to your estimate of 900 million years) after all, I do not believe that RNA is too terribly complex.
There is a chance that the “cellular” microfossils found soon after the Earth cooled are not actually CELLS, but cell-like structures called proteinoid microspheres.
“Proteinoids” are short protein-like molecules formed by baking amino acids under ultraviolet light. Proteinoid microspheres form very easily (just take a hot lump of proteinoids and dump them in salt water for a few minutes). Proteinoid microspheres are about a micron across, the same size as many small bacteria, and display many of the same properties as living cells: they have a “membrane” that protects their interiors, they “eat” material from the surrounding environment, and they “divide” into two smaller proteinoid microspheres when they get too big. The only thing keeping us from classifying proteinoid microspheres as “alive” is the absence of actual genetic material (RNA or DNA).
If the super-ancient microfossils are actually proteinoid microsphere remnants and not bacterial remnants, self-replicating strands of RNA may indeed have been the first “life.” Maybe some RNA got “gobbled up” by proteinoid microspheres and entered into a symbiosis with it, much like mitochondria are thought to have been purple bacteria that entered into a symbiotic relationship with proto-eukaryotes.