2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/126606This letter reports complete sets of two-fold symmetries between partitions of the universal genetic code. By substituting bases at each position of the codons according to a fixed rule, it happens that properties of the degeneracy pattern or of tRNA aminoacylation specificity are exchanged.Accepted for publication in the Journal of Theoretical BiologyOther Quantitative Biologytext