Converstion of food to energy is the process where metabolism begins.
Metabolism is a set of life sustaining chemical reactions within cells of an organism with three purposes:
- Produce energy to run the cellular processes,
- Build building blocks of lipids, proteins, carbohydrates, etc. and
- Eliminate nitrogenous wastes.
Enzymes act as catalysts in these reactions. These reactions allow organisms to grow, reproduce, sustain life and respond to external environment.
Here we are going to discuss the first process of energy production only. There are two ways it happens: aerobic and anaeraobic. The former is in the presenece of oxygen and the latter in the lack of oxygen.