Exchange surfaces

• Large biological molecules are hydrolysed into smaller molecules that can be absorbed across cell membranes
• Amylase is produced in the pancreas and salivary glands (Carbs)
• Amylase hydrolyses polysaccharides into the disaccharide maltose by hydrolysing glycosidic bonds

  • Begins in the mouth
  • Continues in the duodenum
  • Completed in the ileum
• Proteins - Larger polymer molecules - 3 Enzymes

  • Endopeptidase (middle) - Hydrolyses peptide bonds between amino acids in the middle of a polymer chain
  • Exopeptidase (end) - Hydrolyses peptide bonds between amino acids at the end of a polymer chain
  • Membrane-bound dipeptidase - Hydrolyses peptide bonds between two amino acids
• Protein digestion:

  • Starts in the stomach
  • Continues in the duodenum
  • Fully digested in the ileum
• Lipase is produced in the Pancreas, it can hydrolyse the ester bonds in triglycerides to form monoglycerides and fatty acids
• Physical (emulsification and micelle formation)

  • Coated in bile salts to create an emulsion
  • Many small droplets of lipids provide a large SA to enable the faster hydrolysis action by lipase
• Chemical (lipase)

  • Lipase hydrolyses lipids into glycerol and fatty acids (some monoglycerides)