Symmetries of the standard genetic code at the first stage of its evolution

The formation of the Standard Genetic Code (SGC) represents a distinct, pronounced phase of biological evolution, during which a mechanism was established for the precise correspondence between the trinucleotide units of the source of genetic information and their acceptors - amino acids (AAs) - capable, as part of a polymer, of forming three-dimensional structures with efficient catalytic and other properties essential for the existence of cellular life. The presented material illustrates the author's hypothesis regarding two stages of SGC evolution, the culmination of each being characterized by two types of symmetries. The evolution of the SGC consists of the increasing structural complexity from Stage 1 to Stage 2, the enrichment with new coding products, and the refinement of the symmetries that characterize each stage. These symmetries may not only illustrate this evolution but also serve as one of its driving forces. The symmetries of the SGC presented in this work are too strict to be random and too redundant to be an indispensable condition for its noise immunity and stability. These symmetries are as much a textbook characteristic of the SGC as noise immunity and stability. The emphasis of this work is placed on the first Stage (Stage 1) of SGC evolution, which is why it is indicated in the title. This points to the prospect of a subsequent work focusing on Stage 2, which has its own distinctive features.