Digestive Enzymes

• Enzymes

  Catalyze chemical reactions, speed them up
• Enzymes

  • Large protein molecules
  • Have a groove on their surface called the active site
  • The active site is where the substrate attaches
• Substrate

  The molecule that the enzyme breaks down
• Substrate fits into active site


  Enzyme can break down substrate
• Substrate does not fit into active site


  Enzyme cannot break down substrate
• Lock and key theory


  Enzymes are specific, the substrate must fit perfectly into the active site
• Proteases


  • Enzymes that break down proteins
  • Found in the stomach, pancreatic fluid, and small intestine
• Proteins


  Long chains of chemicals called amino acids
• Protein digestion


  1. Proteases convert proteins back to individual amino acids

  2. Amino acids are then absorbed into the bloodstream
• Carbohydrases


  • Enzymes that break down carbohydrates
  • Amylase breaks down starch
• Starch


  A carbohydrate consisting of a chain of glucose molecules
• Amylase


  • Found in saliva and pancreatic fluid
• Lipase


  • Enzyme that breaks down lipids
  • Found in pancreatic fluid and small intestine
• Lipids


  Molecules consisting of glycerol attached to 3 fatty acids
• Lipid digestion


  Lipase breaks down lipids into glycerol and fatty acids
• Bile


  • Made in the liver, stored in the gallbladder
  • Not an enzyme, but helps speed up lipid digestion by lipase
• Bile


  Converts large lipid droplets into smaller droplets, increasing surface area for lipase
• Bile


  Alkaline, neutralizes stomach acids, creating alkaline conditions for lipase