Molecular Evolution of Life on Earth  [Current Thinking]
             a theoretical link between a metabolism 1st & a genetics 1st origin hypotheses?
1.  Research of last 50 years supports how a primordial soup may have created the building blocks
    (both amino acids & nucleotides) which became the proteins & nucleic acids necessary to create single cells.
2.  Unknown - how protein polymers were assembled according to today's coded nucleic acids templates ? 
     Probable hypothesis: an RNA World gave rise to 1st short peptides, which were encapsulated into protocells ?
3.  New alternative:  an ancient family of proteins (precursors to today's 20+ Aminoacyl-tRNA Synthetases,
                                 also called tRNA ligases and abbreviated aaRS's) recognize amino acids during translation,
                                 these Ligase enzymes join together (ligate) aa's & tRNA with splitting of ATP.
      Two of these ancient aaRS's are now known to have been coded by opposite complementary strands of one gene,
      suggesting an early evolutionary origin of gene action, which may have given rise to a PEPTIDE-RNA WORLD.
                               complementary strands                 

      All of todays aaRS's are related evolutionarily to these two initial aaRS's,
                                    thus molecular evolution might have been a joint combinatorial effort
                                    of metabolic and genetic origins for a PEPTIDE-RNA World.  
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