INPUT-OUTPUT MODELS OF BIOLOGICAL SYSTEMS - FORMULATION AND APPLICABILITY

An input-output model of a biological system can be made using qualitative data on the metabolism and quantitative data on the composition of the system. It describes the relations between various components of the system in terms of mass and energy transfer and is mathematically identical to Leontief's input-output model of economic structure. While input-output models are not as accurate and do not provide as much information as kinetic or equilibrium models, it is possible to construct an input-output model of a system about which too little is known to permit building either of the latter models, and to obtain from it estimates of biosynthetic enzyme activities and energy requirements for growth. The technique is demonstrated using a model of Escherichia coli. Applications of the data obtained from input-output models to development of selective histochemical techniques and in chemotherapy are discussed. The possible use of the Leontief model and the economical model of von Neumann in the study of optimizing behavior in biological systems is also discussed. © 1969.