Enzymes
Most chemical reactions require energy to begin The amount of energy needed to start the reaction is called activation energy 2
Biological catalysts are called enzymes Certain chemical substances (catalysts) reduce the amount of activation energy required Biological catalysts are called enzymes 3
Enzymes are an important class of catalysts in living organisms Mostly protein Thousands of different kinds Each specific for a different chemical reaction 4
Enzyme Structure Enzymes work on substances called substrates Substrates must fit into a place on an enzyme called the active site Enzymes are reusable! 5