Fig. 9From: The Origin and Evolution of Metabolic Pathways: Why and How did Primordial Cells Construct Metabolic Routes?The patchwork hypothesis on the origin and evolution of metabolic pathways. a The origin of enzymes with narrowed specificity from an ancestral unspecific one. b Hypothetical overall structure of the metabolic pathways (MP) in which enzymes (E0, E1, E2, E3) are involvedBack to article page