... be made up of different configurations of polypeptide chains. There are secondary, tertiary and quaternary structures (i.e. haemoglobin) protein molecules which increase respectively in complexity. Proteins contain an 'R-group' which is specific to each amino acid, this part of the molecule is the active site. Enzymes lower the activation energy needed for chemical reactions and allow the reactions to occur rapidly at the relatively low temperature of living things, without enzymes the high metabolic rates in organisms would not exist. An enzyme decreases the activation energy so that the substrate molecules have energy greater than, or can easily reach the new activation energy and therefore the rate of reaction increases. For this to occur the catalase molecule must collide with the Hydrogen Peroxide molecule in the correct place (active site) for the collision to be successful and produce the products. The random movement of the molecules in the liquid solution ...

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