Origin and evolution of the genetic code: The universal enigma

Abstract The expansion of the standard code according to the coevolution theory. Phase 1 amino acids are orange, and phase 2 amino acids are green. The numbers show the order of amino acid appearance in the code according to (99). The arrows define 13 precursor‐product pairs of amino acids, their color defines the biosynthetic families of Glu (blue), Asp (dark‐green), Phe (magenta), Ser (red), and Val (light‐green). See Origin and Evolution of the Genetic Code: The Universal Enigma by Koonin and Novozhilov, pp. 99‐111.