Science: Biology Unit 2(ii)

-enzymes are catalysts produced by living things. enzymes act as catalysts which speed up chemical reactions, so the temp doesn't have to be raised.

- A catalyst is a substance which increases the speed of a reaction without being changed or used up in the reaction.

-Enzymes: proteins, made up of chains of amino acids->folded into unique shapes. Every enzyme has a unique shape that fits onto the substance involved in a reaction. Enzymes can only usually catalyse one reaction.

-Enzymes need the right temp and pH. Higher temp = reaction rate increases, til it gets too hot and bonds break (denatured). Human enzymes work best at 37C. pH interferes with bonds and changes the shape. Best pH is usually neutral 7.