enzymes

• enzymes are catalysts produced by living things
• a catalyst is a substance which increases the speed of a reaction, without being changed or used up in the reaction
• enzymes are all large proteins and all proteins are made up of chains of amino acids
• enzymes have special shapes so they can catalyse reactions
• every enzyme has an active site with a unique shape that fits onto the substance involved
• the active site changes shape slightly as the substrate binds to it to get a tighter fit. this is called the induced fit model of enzyme action
• changing the temperature changes the rate of an enzyme-catalysed reaction
• if the temperature gets too hot, some of the bonds holding the enzyme together break. this changed the active site of the enzyme, not allowing it to do its job anymore
• the pH affects enzymes. if it's too high or too low, the pH interferes with the bonds holding the enzyme together.
• all enzymes have an optimum pH that they work best at