Final answer:
Cells use enzymes and substrates to facilitate the building up and breaking down of molecules in metabolic processes; enzymes act as catalysts and substrates are the molecules being transformed.
Step-by-step explanation:
The two different chemical substrates and enzymes accomplish the processes of building up and breaking down molecules in cells. An enzyme is a protein that acts as a biological catalyst, and it plays a crucial role in controlling cellular metabolism by speeding up the reactions that occur within the cell. A substrate is the molecule upon which an enzyme acts, and it can be either built up (anabolic reactions) or broken down (catabolic reactions) in this process.