The transit time and a characteristic time constant for the transition time are formulated for a pathway unit of Michaelis-Menten mechanism in metabolic chains with mass-action-type dependence. The pathway unit in a chain is assigned to each metabolite and two consecutive Michaelis-Menten-type reactions associated with it. All the relevant functions such as control coefficients, elasticities and transit time for the pathway unit are expressed in terms of the flux J and other system parameters. The transition time is characterized by a time constant for a first-order system expressed as the derivative of the total concentration of the internal metabolite with respect to the flux J.