BIOL380 Week 5 Cell Junctions

  1. Define Cell Junctions.
    They are connections between one cell and its extracellular environment or between one cell and a neighboring cell.
  2. What are the 3 Categories of Cell Junctions?
    • Occluding Junctions
    • Anchoring Junctions
    • Communicating Junctions
  3. Define Occluding Junctions
    Occluding Junctions are junctions that prevent (occlude) molecules from passing between two cells.
  4. Define Anchoring Junctions
    Anchoring Junctions serve as anchorings connecting one cell to another cell or to the extracellular matrix.
  5. Define Communicating Junctions
    Communicating Junctions between two cells allow intracellular molecules to move from one cell to another. Allows communication.
  6. What are the 2 Types of Occluding Junctions
    • Septate Junctions
    • Tight Junctions
  7. Which type of Occluding Junction is present in Vertebrates?
    Tight Junctions
  8. Which type of Occluding Junction is present in Invertebrates?
    Septate Junctions
  9. What two major transmembrane protein families make up Tight Junctions?
    • Occludin
    • Claudin
  10. What is the function of the protein Occludin?
    To prevent materials from passing between two cells
  11. What is the benefit of Occluding Junctions?
    Occluding Junctions keep the separation between the body and the environment resulting in selective uptake of particular molecules.
  12. What are the two protein families that make up Anchoring Junctions?
    • Cadherin Family
    • Integrin Family
  13. What type of structural protein within the cell is attached to the Anchoring Junction proteins?
    • Actins
    • Intermediate Filaments such as Keratin
  14. Define Extracellular Matrix
    The non-cellular complex of proteins and carbohydrates; think of as foundation for the cell.
  15. Other than Proteins and Carbohydrates, what else could the Extracellular Matrix include?
    • Glycosaminoglycans or Cellulose
    • Collagen
  16. What are 3 functions of Extracellular Matrix?
    • Support
    • Assit in Cell Migration
    • Cell Recognition
  17. What are 4 types of Anchoring Junctions?
    • Adherens Junctions
    • Focal Junctions
    • Desmosomes
    • Hemidesmosomes
  18. What is the function of the Adheren Junction?
    To connect cells to cells
  19. What proteins make up Adheren Junctions?
  20. How is the Adheren Junction attached to the Cell?
    Cadherin proteins are attached to Actin via Linker Proteins
  21. Why are Linker Proteins significant?
    For coordinated actions like the development of the nervous system.
  22. What is the function of Focal Adhesions?
    Connects the Cell to Extracellular Membrane
  23. What protein family form the Focal Adhesion Junctions?
    Integrin family
  24. What are the Linking/Anchoring Proteins for Focal Adhesion Junctions?
    • Actinin
    • Filamin
    • Talin
  25. What is the function of the Desmosome?
    connects one Cell to another Cell
  26. What proteins form Desmosomes?
  27. How are Desmosomes attached to the Cell?
    Via Intermediate Filaments (Keratin)
  28. What are the Linking/Anchoring Proteins for Desmosomes?
    • Desmoplakin
    • Plakoglobin
  29. What are the Cadherin proteins that form the Desmosome junction?
    • Desmoglein
    • Desmocollin
  30. What is the function of the Hemidesmosome?
    Connects cell to Extracellular Matrix
  31. What protein family makes up the Hemidesmosome Junction?
  32. How does the Hemidesmosome Junction attach to the cell?
    Via Intermediate Filaments (Keratin)
  33. What are the two types of Communication Junctions and what do they NOT do?
    • Gap Junctions
    • Plasmodesmata
    • They do NOT connect one cell to another cell
  34. Define Gap Junction
    Similar to a Channel but allow material to go from a cytoplasm of one cell to the cytoplasm of another cell.
  35. What proteins form Gap Junctions?
  36. What is needed from each cell (of the pair) in order to establish a Gap Junction?
    One Connexon from each cell
  37. How many transmembrane proteins join together to form the Connexon?
  38. The 6 transmembrane proteins that form the Connexon are called what?
  39. If you have 6 of the same Connexin, what type of Connexon do you have?
    Homomeric Connexon
  40. If you have 6 different Connexins, then you have what kind of Connexon?
    Heteromeric Connexon
  41. If you have 2 Connexons that are the SAME, what kind of Channel do you have?
  42. If you have 2 Connexons that are DIFFERENT, what kind of Channel do you have?
  43. What passes through Gap Junctions?
    • Ca++ Ions
    • Small Hydrophilic Molecules (<1000 Daltons)
    • Water in Small Amounts
  44. Plasmodesmata Junctions are present in what kind organism and structure?
    Cell Wall of Plants
  45. What is the function of the Plasmodesmata Junction?
    Allows similar molecules to pass from one cell to another
  46. The Plasmodesmata Junction is similar to what other type of junction?
    Gap Junction
  47. What is the Desmotubule?
    A small organelle component tubule that passes through the cell walls of two cells which connect the Smooth Endoplasma Reticulum.
Card Set
BIOL380 Week 5 Cell Junctions
BIOL380 Week 5 Cell Junctions