Enzymes are proteins that act as biological catalysts, where they are organic compounds and speed up reactions. Enzymes increase the rate of reaction without taking part. Enzymes are specific, where they act on only one substrate as most of them only catalyse one reaction. When an enzyme attaches to the substrate at its active site, it creates an enzyme-substrate complex. Enzymes are folded into a 3D shape which creates active sites where the enzyme works. The active site is the place where the substrate will attach to an enzyme and catalyse chemical reactions. The lock and key mechanism suggests that when the right substrate enters the active site, the chemical reaction will occur more quickly because the substrate will fit perfectly into