In cells, metabolism involves two following types of pathways:
a. Catabolic pathways
This involves formation of simpler structure from a complex biomolecule.
For e.g. when we eat wheat, bread or chapati, our gastrointestinal tract digests (hydrolyses) the starch to glucose units with help of enzymes and releases energy in form of ATP (Adenosine triphosphate).
b. Anabolic pathway
It is also called as biosynthetic pathway that involves formation of a more complex biomolecules from a simpler structure
Fone.g., synthesis of glycogen from glucose and protein from amino acids. These pathways consume energy.