The proposed model for a ‘realistic hypercycle’ is closely associated with the molecular organization of a primitive replication and translation apparatus. Hypercyclic organization offers selective stabilization and evolutive adaptation for all geno- and phenotypic constituents of the functionally linked ensemble. It originates in a molecular quasi-species and evolves by way of mutation and gene duplication to greater complexity. Its early structure appears to be reflected in: the assignment of codons to amino acids, in sequence homologies of tRNAs, in dual enzymic functions of replication and translation, and in the structural and functional organization of the genome of the prokaryotic cell.