Enzyme activity
How enzymes catalyse biological reactions
Enzymes act on substrates by attaching to them. The part of an enzyme that one or more substrates molecules can attach to is called the The part of the enzyme to which a specific substrate can attach or fit on to..
The diagram below shows how an enzyme catalyses the A breakdown reaction - when a chemical compound splits into smaller parts. (breakdown) of one substrate into two products.
Enzymes can also catalyse the A build-up reaction - when two or more substances join together to form one product. (joining together) of two substrates to form one product.
For example, the enzyme phosphorylase catalyses the synthesis of glucose-1-phosphate (the substrate) to form starch (the product). Watch the video below to see the correct procedure for carrying out an investigation into this reaction.
Enzyme specificity
Each different type of enzyme will usually catalyse one biological reaction. Enzymes are specific because different enzymes have different shaped active sites.
The shape of an enzyme's active site is complementary to the shape of its specific substrate or substrates. This means they can fit together.
Science presenter Jon Chase demonstrates the action of the enzyme catalase, produced by the liver, in breaking down hydrogen peroxide into water and oxygen.