Digestive and absorption

• Describe how proteins are digested in the human gut

  • hydrolysis of peptide bonds
  • endopeptidases break polypeptides into smaller peptide chains
  • exopeptidases remove terminal amino acids
  • dipeptidases hydrolyse dipeptides into amino acids
• What is the role of exopeptidases?


  hydrolyse peptide bonds on terminal amino acids
• what is the role of membrane-bound dipeptidases?

  hydrolyse dipeptides into 2 amino acids
• what is the role of endopeptidases?

  hydrolyse peptide bonds in middle of polypeptide chain.

  breaks polypeptide down into smaller peptide chains
• Describe the processes involved in the absorption and transport of digested lipid molecules from the ileum into lymph vessels

  • micelles contain bile salts and fatty acids/monoglycerides

  • micelles bring products to lining of ileum and are broken down when in contact with epithelium

  • fatty acids/monoglycerides absorbed by diffusion

  • triglycerides reformed at ER

  • in golgi, formed chlyomicrons

  • packaged in vesicle and transported to cell membrane

  • moves out of cell by exocytosis into lymph vessel
• Explain the advantages of lipid droplet and micelle formation 


  • droplets increase surface area so easily hydrolysed by lipases

  • faster digestion of triglycerides

  • Micelles carry fatty acids and monoglycerides to cells lining ileum
• Why are fatty acids and monoglycerides able to diffuse across the membrane?


  They’re non-polar and lipid-soluble