To analyze a biological system it is necessary to find out new mathematical models allowing to explain the evolution of the system in a dynamic context or to dread doing of a simple manner the complex situations where the human experience overtakes the mathematical reasoning. Computers have been used since the 1940 to simulate the kinetics of Biochemical reactions. Using a pathway structure and a kinetic scheme, the time of reaction and the admissible steady states can be computed. The majority of kinetic models are described by coupled differential equations and simulators implement the appropriate methods to solve these systems. Our goal is to analyze, to understand and to modeling these systems of reactions and the mechanisms that govern them, so as to better apprehend the behavior of cells.