Enzymes are Catalysts produced by Living Things
A CATALYST is a substance which INCREASES the speed of reaction, without being CHANGED or USED UP in a reaction
Enzymes are all proteins and all proteins are made up of chains of amino acids. These chains are folded into unique shaoes, which need to de their job
A substrate us a molecule that is changed in a reaction. Every enzyme molecule has an active site which the substrate must be the right size to fit into. This can be shown with a lock and key model.
Enzymes like it warm but not too much. Changes in temperature chages the rate of an enzyme- catalysed reaction. A higher temperature increases the rate at first. If it gets too hot some of the bonds holding the enzyme together will break. This makes the enzyme lose its shape which means the substrate won't fit into its active site. This means the enzyme is denatured.pH also effects enzymes. Optimun is often pH7.