9.2.3 Enzyme Structure

• Chemical digestion


  The breakdown of large, insoluble molecules into small, soluble molecules
• Enzymes


  Proteins that function as biological catalysts
• Catalysts

  Molecules that speed up a chemical reaction without being changed by the reaction (i.e. they are not used up)
• Enzymes

  • They have a specific shape
  • They have an active site that a substrate will fit into
  • The active site and the substrate are complementary in shape

  
• Enzyme-controlled reactions

  • Respiration (plants and animals)
  • Photosynthesis (plants only)
  • Digestion (animals only)
• Enzyme-substrate complex

  1. Enzyme and substrate collide

  2. They make an enzyme-substrate complex

  
• Lock and key hypothesis

  Enzymes have a specific shape for the substrate

  
• Enzymes that break down different substances

  • Amylase breaks down starch
  • Proteases break down proteins
  • Lipases break down lipids

  
• The pancreas produces amylase, protease and lipase