BIOL 404-Exam 4-GI 5

  1. What are the three enzyme types that break peptides into AAs?
    • Carboxypeptidase
    • Aminopeptidase
    • Cytoplasmic peptidase
  2. Carboxypeptidases, Aminopeptidases and Cytoplasmic peptidases have what activities?
    Breaking peptides into AAs
  3. What are the three locations for protein digestion
    • 1. In the intestinal lumen.
    • 2. At the brush border of the intestinal mucosa.
    • 3. In the cytoplasm of the enterocytes.
  4. What does Elastase do?
    Breaks down proteint o AAs and oligopeptides
  5. After proteins are broken down to oligopeptides, what happens to them?
    hydrolyzed by integral membrane proteins of the brush border
  6. What are the two types of enzymes that breakdown oligopeptides?
    • Endopeptidases
    • Ectopeptidases
  7. What do endopeptidases do?
    Cleave internal bonds of oligopeptides
  8. What do Ectopeptidases do?
    Cleaves the ends of oligopeptides and dipeptides
  9. What types of protein products can be absorbed?
    • Dipeptides
    • Tripeptides
    • Amino Acids
  10. Transport of protein products into the cell is likely linked to what type of ion transporter?
    H ion transporter
  11. After absorption, what happens to di and tripeptides?
    The bulk are cleaved to AAs by cytosolic peptidases
  12. Are all di and tripeptides broken down in the cytoplasm of the enterocytes?
    • No,
    • Some dipeptides and tripeptides escape intracellular proteolysis and are transported across the enterocyte basolateral plasma membrane intact
  13. Where does absorption of protein products occur?
    Primarily in the upper small intestine
  14. Can intact protein be absorbed into the small intestine?
    • Yes, in very small amounts
    • Via endocytosis and exocytosis
  15. What type transport is needed to move free AAs into the endocytes?
    Secondary active transport coupled with Na
  16. What type of protein product requires secondary active transport coupled with protein?
    Free AAs
  17. By what mechanism are di/tripeptides carried into the endocytes?
    Secondary active transport coupled with H ions
  18. Secondary active transport coupled with H ions carries what protein product into the enterocyte?
    Di and Tri-peptides
  19. How are Di and Tri-peptides carried out of the endocytes?
    Facilitated diffusion
  20. Are dipeptides, tripeptides or AAs absorbed more rapidly?
    Di and Tri-peptides
  21. What provides the radiant for secondary active transport of protein products?
    Na/K ATPase in the basolateral membrane of the enterocytes
  22. How do AAs exit the enterocyte?
    carrier protein mediated facilitated transport
  23. Trypsin is a protein digesting enzyme that is secreted where?
    The exocrine cells of the pancreas
Card Set
BIOL 404-Exam 4-GI 5
BIOL 404-Exam 4-GI 5