biological catalysts

• • enzymes speed up chemical reactions by acting as a biological catalyst. they catalyse metabolic reactions bot at cellular level and for the organism as a whole
  • enzymes can effect structures in an organism as well as function
  • enzyme action can be intracellular (in) or extracellular (out)
• intracellular enzyme example - catalase

  • hydrogen peroxide is the toxic by-product of several cellular reactions, it can kill cellscatalase is an enzyme that works inside cells to catalyse the breakdown of hydroge peroxide to harmless o2 and water
• • extracellular enzyme examples - amylase and trypsin
  • both work outside the cells in the human digestive system
  • amylase is in saliva. its secreted into the mouth by cells in the salivary gland. catalyses the hydrolysis of starch into maltose in the mouth
  • tripsin catalyses the hydrolysis of peptide bonds - turning big polypeptides into small ones. trypsin is produced by cells in the pancreas and secreted into the small intestine
• enzymes are globular proteins
• enzymes have an active site which has a specific shape. the active site is part of the enzyme that the substrate molecules bind to
• specific shape of the active site is determine by the enzmes tertiary structure
• for the enzyme to work, the substrate has to fit into the active site. if it dosent the reaction wont be catalysed and the enzyme will work with very few substrates