What is an enzyme and how do they work?

An enzyme is a protein that speeds up a chemical reaction. For example, the food you had for your lunch today was probably made up of complex carbohydrates, proteins and lipids. These need to be broken down in order for your body to absorb and utilise them. This is where enzymes come into play! However enzymes aren't just found in your digestive system but are found in all living organisms. They can also build chemical molecules as well as break them down. Enzymes have complex 3D structures and have a region known as an active site. This active site will bind a molecule/molecules known as the substrate. Once the substrate has bound to the active site a chemical reaction can take place and a product released. Enzymes are very specific and will only bind the substrate that fits perfectly into it's active. Think of it like a lock and a key. Only one key will fit into one lock!