The role of enzymes
Enzymes are polypeptide chains of amino acids (protein) that are required in order to allow some chemical reactions to take place at body temperature. Enzymes have an area called an active site which is a complementary shape to the substrate that it is catalysing. They work by forming an enzyme substrate complex which lowers the activation enthalpy for the break down/reaction of the molecule. With out enzymes, many body reactions will not take place as the body is not hot enough to provide the substrates with enough energy in order for a reaction to take place. Furthermore, the enzyme must have a perfectly complementary active site that can hold the substrate. As a result, enzymes usually only catalyse the reaction/break down of one or very few substrates.
I can't write any more as i have work now. Haha! This is what i remeber from memory so please check this information to make sure it is accurate. I'm sure it is accurate, but please check as i'm not 100% sure.
I will answer the rest tonight.
I hope this helps.
Kade