What are enzymes and how do they work?

Enzymes are small proteins found in living organisms. They are described as biological catalysts, meaning they speed up reactions and remain unchanged at the end, ready to do the same again. They are vital for life because almost every metabolic reaction requires an enzyme to be able to go ahead.They work by lowering the activation energy of a reaction. Activation energy is needed to start any reaction, and one way of creating it is by heating up the substrates. Adding an enzyme means it takes less energy for the reaction to take place, meaning they can happen more efficiently, at a faster rate.