Boreskov

the pairs of the “very first” (Miller’s) amino acids, such as Gly and Ala with the acceptormorethan anticodon‐sensitive risk of wrong recognition (Rodin & Rodin, 2006, 2008; Rodinet al., 2009).Taken together, our findings (Rodin et al., 1993‐2011) question many dogmas of thecode and translation origins. First and above of all, primordial tRNAs, ribozymic precursors ofaaRSs, and (later) the translation machinery as a whole seem to have been co‐evolving to“fit” the (likely already defined) genetic code rather than the opposite way around. Codingtriplets in this primal pre‐translational code were similar to the anticodons, with second andthird nucleotides being more important than the less specific first one. Later, when the codewas expanding in co‐evolution with the translation apparatus, the importance of 2‐3nucleotides of coding triplets passed on 1‐2 nucleotides of their complements, thusdistinguishing anticodons from codons.The statistically compelling bias to anticodon(2‐3)/codon(1‐2) tetraplets in aa‐bindingsites of RNA aptamers points to a fundamental interconnection between the primordial RNAoperational code (hence the genetic code itself) and a chiral selection of its components.Indeed, in model ribooligonucleotides‐assisted aminoacylation of RNA minihelices, selectionof L‐amino acids was determined by a pre‐selected D‐ribose, and vice versa (Tamura &Schimmel, 2004, 2006). An intriguing question would be: what if, with a fascinating mirrorsymmetry, the chiral‐mirror RNA world (with L‐ribose and D‐amino acids) is just theanticodon(1‐2)/codon(2‐3) biased? The mirror “selexed” RNA aptamers could provide ananswer. The experiments that might test the possibility of such a mirror symmetric life areoutlined.All of the above make the following key hypotheses in the area – (1) stereo‐chemicalaffinity between amino acids and anticodons (Woese, 1965; Orgel, 1968, Yarus, 1998), 2)coding coenzyme handles for amino acids (Szathmary, 1990, 1993), 3) tRNA‐like genomic 3’tags (Weiner & Maizels, 1987, 1994) implying that tRNAs originated in replication, 4) the“second” (operational) genetic code of proto‐tRNA aminoacylation (De Duve, 1988;Schimmel et al., 1993), in its ancient ribozyme‐mediated version, and 5) SAS (sense/antisense)origin of two aaRS classes (Rodin & Ohno, 1995) and the yin/yang‐like internal codefor their sterically mirror modes of tRNA recognition (Rodin & Rodin, 2006, 2008) – notmutually contradicting but co‐existing in harmony and essentially add to the fundamentalpremise: Translation without code does not make sense, but code without (and before)translation does!113