Characterisation of blocked reactions in RECON 1. A) Classification of blocked reactions in RECON 1 depending on their causative dead-end metabolite. B) The cellular distribution of dead-end metabolites, blocked reactions, and blocked reaction cascades within cellular compartments accounted for in RECON 1. C) The metabolic pathway distribution of the 175 blocked reactions investigated. D) The distribution of BiGG database confidence scores for the blocked reactions investigated. 3 = biochemical and or genetic evidence, 2 = physiological evidence or evidence from a nonhuman mammalian cell, 1 = modelling evidence, 0 = unevaluated.