What substances are called catalysts and what role do they play in the cell?

Enzymes are large molecules that speed up chemical reactions inside cells. Each type of enzyme works for a specific job. Enzymes are a type of protein, and like all proteins, they are made from long chains of different amino acids. Enzymes are soluble protein molecules that can speed up chemical reactions in cells. These reactions include respiration, photosynthesis, and the creation of new proteins. For this reason, enzymes are sometimes referred to as biological catalysts. Enzymes accelerate (catalyze) chemical reactions that take place inside and outside living cells.