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
• Protein digestion

  Proteases break down proteins into amino acids
• Proteases

  • Found in stomach, pancreatic fluid, small intestine
• Proteins


  Long chains of amino acids
• Starch digestion

  Amylase breaks down starch into simple sugars
• Amylase

  • Found in saliva, pancreatic fluid
• Starch

  Chain of glucose molecules
• Lipid digestion

  Lipase breaks down lipids into glycerol and fatty acids
• Lipase

  • Found in pancreatic fluid, small intestine
• Lipids

  Molecule of glycerol attached to three fatty acids
• Bile

  • Made in the liver, stored in the gallbladder
  • Not an enzyme, but helps speed up lipid digestion by lipase
  • Converts large lipid droplets into smaller droplets, increasing surface area
  • Alkaline, neutralizes stomach acids, creates alkaline conditions in small intestine
• 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
• Protein digestion

  1. Proteases in stomach, pancreatic fluid and small intestine

  2. Convert proteins to individual amino acids
• Proteins

  Long chains of chemicals called amino acids
• Starch digestion

  1. Carbohydrases, specifically amylase in saliva and pancreatic fluid

  2. Break down starch (chain of glucose molecules) into simple sugars
• Lipid digestion

  1. Lipase in pancreatic fluid and small intestine

  2. Break down lipids (glycerol attached to fatty acids) into glycerol and fatty acids
• Lipids

  Molecule of glycerol attached to three molecules of 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, creates alkaline conditions in small intestine to increase lipase activity