Doing daily activities need energy. The energy occurs in foods. The food, for e.g rice does not give body the needed energy. But it needs to break down into a chemical compounds in body. This process is called metabolism.



Every molecules have their process/pathway. Forming what is needed or breaking down what is needed. In body the molecules also doing an interrelationships to form energy.

There are three main pathway of metabolic
(1) Anabolic pathways, which are those involved in the synthesis of larger and more complex compounds from smaller precursors—for example, the synthesis of protein from amino acids and the synthesis of reserves of triacylglycerol and glycogen. Anabolic pathways are endothermic.

(2) Catabolic pathways, which are involved in the breakdown of larger molecules, commonly involving oxidative reactions; they are exothermic, producing reducing equivalents, and, mainly via the respiratory chain , ATP.

(3) Amphibolic pathways, which occur at the “crossroads” of metabolism, acting as links between the anabolic and catabolic pathways, for example, the citric acid cycle.