Golgi, Endosomes, and Membrane Trafficking S1M1

  1. What are the three different destinations for Golgi shipments
    • Lysosomes (signal mediated)
    • Plasma Membrane (Default destination)
    • Secretory Vesicles (signal mediated)
  2. Vesicular transport from the golgi ships what materials
    Membrane proteins, soluble proteins, and lipids
  3. In what portions are machinery needed in vesicular transport
    • 1. To promote visicle budding
    • 2. To target the correct membrane
    • 3. To promote visicle fusion
  4. In order for budding on the Golgi to take place, what machinery is necessary
    • One of three coat proteins.
    • Clathrin, COPI, COPII
    • (Caveolin for caveolae could be considered a fourth)
  5. How does COP II differ from COP I as a coating protein
    • COP II performs packaging of transfer of vesicles from the Rough ER to the cis-Golgi only
    • COP I mediates transfer of vesicles through Golgi stacks, and constitutive secretion to plasma membrane (also retrograde transport from Golgi back to ER)
  6. What is Clathrins role in protein coating
    Clathrin mediates endocytosis of vesicles from the plasma membrane, and movement from the trans-golgi to lysosomes secretory vesicles
  7. What is a V-snare (Vesicle) and a T-snare (Target Membrane)
    T-snares are on the target memberane, and V-snares are on the vesicle. When they match up, fusion happens. (Yin Yang kind of deal)
  8. Why are snares not found on peroxisomes or mitochondria
    Because they use other methods like endocytosis and don't need them
  9. What are a Rabs
    They are small proteins that connect with a tethering protein on the target membrane which pull the rabs in like an arm
  10. How are the the snares removed
    NSF and SNAPs break them apart
  11. What is the golgi apparatus
    A membrane bound organelle in eukaryotes where proteins and lipids transfered from the ER are modified and sorted
  12. What is the difference between the trans face and the cis face of a golgi
    The cis face is closer to the ER
  13. As proteins move through the Golgi what happens to the carbohydrate
    The N-linked carbohydrate is trimmed and they receive additional O-linked sugars
  14. What acid group gives the plasma membrane of the golgi exterior its negative charge
    Sialic acid (The only carb with a neg charge)
  15. Where are glycolipid formed
    They are formed in the Golgi
  16. Where is there no glycosylation
    On the cytosol side of the membrane
  17. What is the glycocalyx
    A thick protective rim of carbohydrate around the plasma membrane, also known as a cell coat and is important to cellular recognition
  18. Transgolgi is used for what
    It is considered the sorting station like that of UPS
  19. What is required to secrete a hormone such as insulin and neurotransmitters
    They require a chemical signal to release
  20. How can the MT's assist with vesicle secretion
    They can use the Dynein and Kinesin to move the visicles to the actin to finish the secretion
  21. What effect can the rise of calcium have in the cytoplasm relating to vesicles
    The rise of Ca often triggers the release of secretory vesicles from actin binding proteins
  22. What is spontaneous aggregaion
    A collection of proteins in a vesicle that seems to be a major stimulus in regulated vesicles
  23. Why are regulated secretory vesicles often darker when viewed in an electron microscope
    Due to the aggregation of the contents in the vesicle
  24. What does the presence of mannose 6-phosphate (M6P) have on lysosomes
    It is a signal for targeting newly synthesized lysosomal hydrolase in the trans-Golgi to lysosomes
  25. KDEL sequence does what
    It is a permanent retention signal for the ER (BiP has one)
  26. Does Golgi have retention signals
    Yes, but only some have been identified
  27. Lectins in the lumen of the Trans golgi
    Help to stabilize the lipid rafts
  28. Where do the components of a lipid raft (some produced in the ER) begin to coalesce
    In the trans golgi network
  29. GPI linked proteins cluster in
    Lipid rafts (calveolae)
  30. Lipid rafts cosist of
    • Cholestrol
    • Sphingomyelin
    • Phosphatidylcholine
  31. Raft vesicles extruding from the golgi traffic to the surface where they can
    Separate into smaller raft compartments
  32. Exocytosis
    The process by which most molecules are secreted from a eukaryotic cell. These are packaged by membrane bound vesicles that fuse with the plasma membrane releasing their contents
  33. Is Exocytosis used only for garbage
    No, newly synthesized or recycled membrane proteins are taken to the membrane sometimes
  34. Endocytosis
    The uptake of material into a cell by an invagination of the plasma membrane. A drop of extracellular fluid always accompanies
  35. What are the three types of endocytosis
    • Phagocytosis - cell eating
    • Pinocytosis - cell drinking
    • Receptor mediated endocytosis - has to be opsinized
  36. What are some types of opsinization
    • Soluble Chemoattractants released by bacteria
    • Antibody activated (coated with IgG)
  37. Receptor mediated Endocytosis
    A way to take up specific molecules from the extracellular fluid
  38. What are some of the receptors used in receptor mediate endocytosis
    LDL and transferrin
  39. Adaptin
    Proteins on the cytosol side that connect the receptors of a specific binding proteins on the extracellular side through clathrins (Middle man)
  40. What begins the bud formation in receptor mediated endocytosis
  41. Endosomes
    Are the compartments that are the first to receive all endocytoted vesicles
  42. How does an endosome remove receptors from LDL
    It has a relatively low pH that removes them
  43. What happens to receptors used in Endocytosis following the release of LDL
    They return to the cell membrane
  44. What is the difference between the early endosomes and the late endosomes
    • Early endosomes have shed the receptor but not the LDL
    • Late endosomes are essentially lysosomes
  45. Both EGF and ligand receptors are targeted to
    Lysosomes for degradation
  46. What is a primary lysosome
    A cytoplasmic cell organelle that buds off from the golgi complex (becomes a secondary when it fuses with the vesicle containing the matter to be ingested)
  47. EGF receptor
    Is another endocytosis receptor, but differs in that it doesn't invaginate until the target molecule is attached (then it attaches to adaptins), and it doesn't recycle for another round
  48. Caveolae
    Means little caves, and are small invaginations of the plasma membrane in many cell types, especially in endothelial cells
  49. How are caveolae formed
    By lipid rafts that have been invaginated
  50. Where can some of the caveolae go after they pinch off the membrane
    They can deliver contents to the ER and Golgi but never lysosomes
  51. Caveolae are now thought to act as
    Signalsomes, a place where signal transductions can take place efficiently
  52. Many micro organisms like to use caveolae for entry due to
    Their not fusing with lysosomes
Card Set
Golgi, Endosomes, and Membrane Trafficking S1M1
Cell Biology