The collection of all metabolites in a biological organism, which are the end products of its gene expression.

The entire complement of small molecular weight metabolites in a cell

The quantitative complement of all the low molecular weight molecules present in cells in a particular physiological or developmental state. Metabonomics and Metabolomics These very similar terms have arisen at about the same time in different area of bioscience research, mainly animal biochemistry and microbial/plant biochemistry respectively. Although both involve the multiparametric measurement of metabolites they are not identical as metabonomics deals with integrated, multicellular, biological systems including communicating extracellular environments and metabolomics deals with simple cell systems and, at least in terms of published data, mainly intracellular metabolite concentrations.