An electronic circuit has been designed to mimic glycolysis, the Citric Acid (TCA) cycle and the electron transport chain. Enzymes play a vital role in metabolic pathways; similarly transistors play a vital role in electronic circuits; the characteristics of enzymes in comparison with those of transistors suggests that the properties are analagous. Enzymes possess an active site into which the substrate binds, similarly the transistor possess a layer in which the recombination of holes and electrons takes place. Hence the applied voltage in the circuit is considered as the substrate. The enthalpy values of the enzymes are converted into volts, which is to be applied to the circuit. ATP is the energy source in the metabolic pathway which functions like a potential in the electronic circuit. Some enzymes can function only with the help of a cofactor; here modelled as a switch. Using all the above electronic circuit analogues, which possess the similar characteristics of the metabolic pathway constituents, circuits have been designed.