Most of the metabolic processes are today driven by
enzymes, i.e. proteins. This was known long before the genetic systems, with
transcriptions and translation were discovered. Today we know that genetics is
necessary for protein synthesis, but in the first half of the twentieth century
a common thinking about molecular biology was that proteins could somehow
self-replicate. Most scientists today agree that that is not taking place and
has never taken place. But there are still some strange hypotheses claiming
that such processes in early life periods existed, or that proteins could
somehow spontaneously appear in specific sequences.
William Martin and Michael J. Russell have
postulated generation of energy in the form GTP or ATP, and they have
formulated this suggestion:
"Thermodynamic considerations related to formyl
pterin synthesis suggest that the ability to harness a naturally pre-existing
proton gradient at the vent–ocean interface via an ATPase is older than the
ability to generate a proton gradient with chemistry that is specified by
genes."
They have suggested that specific peptide chains
survive better than others, and that enzymes were formed from these. This
suggestion is most probably not possible at all, and it is totally unnecessary,
because life got its energy for formation and handling of RNA molecules in much simpler ways. They suggest that large parts of the metabolic apparatus was
already present, based on these, when the first RNA molecules appeared. A lot
of enzymes are suggested, forming the reverse Krebs cycle and the
Wood-Ljungdahl pathway. But the most improbable and quite teleological
suggestion is that the highly complex membranous ATPase was present before RNA.
This complex changes an RNA molecule from a high energetic to a low energetic
variant or vice versa. The high
energetic variant was on the young earth readily present as pyrophosphate and
other phosphate chains. RNA molecules were built from these.
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