Metabolic Networks, formed by series of metabolic pathways, are made of intracellular and extracellular reactions that determine the biochemical properties of a cell and by a set of interactions that guide and regulate the activity of these reactions. Cancers, for example, can sometimes appear in a cell as a result of some pathology in a metabolic pathway. Most of these pathways are formed by an intricate and complex network of chain reactions, and they can be represented in a human readable form using graphs which describe the cell signaling pathways. In this paper we present a logic, called Molecular Equilibrium Logic, a nonmonotonic logic which allows representing metabolic pathways. We also show how this logic can be presented in terms of a syntactical subset of Temporal Equilibrium Logic, the temporal extension of Equilibrium Logic, called Splittable Temporal Logic Programs.