Enzymes

• Why are enzymes biological molecules?

  They speed up the rate of chemical reactions in living organisms
• Intracellular enzymes

  Produced and function inside the cell ex: catalase
• Extracellular enzymes

  Secreted by cells and catalyse reactions outside cells ex: amylase
• Enzymes have an active site where specific substrates bind forming an enzyme-substrate complex, the shapes of the active site and substrate are complementary
• The enzyme-substrate complex is only formed temporarily, before the products are released
• Catabolic reactions

  They involve the breakdown of complex molecules into simpler molecules, which happens when a single substrate binds to the active site and broken apart into two or more distinct molecules ex: hydrolysis
• Anabolic reactions

  They involve the building of more complex molecules from simpler ones by drawing two or more substrates into the active site, forming bonds between them and releasing a single product ex: photosynthesis
• Enzymes lower the activation energy of a reaction, activation energy is the amount of energy needed by the substrate to become just unstable enough for a reaction to occur and for products to be formed
• Induced fit hypothesis

  Enzymes and substrates interact with each other, the enzyme and it's active site can change shape slightly as the substrate molecule enters the enzyme, this ensures an ideal binding arrangement between the enzyme and substrate, this maximises the ability of the enzyme to catalyse the reaction