cell bio 2c

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cell bio 2c
2013-02-23 13:09:54
cell bio

cell bio
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  1. what kind of proteins with what kind of signals are transported to lysosomes?
    glycoproteins, mannose-6-P chains
  2. what is the purpose of acid hydrolases in acidic organelles?
    breakdown of endocytosed substances and turnover of organelles
  3. how does the cell know to target lysosome?
    • phosphorylate N-linked mannose sugars
    • recognized by man6-P receptors (integral membrane proteins)
    • recognized by adaptors
    • pH sensitive release in endosome/lysosome
    • man 6-P receptors are recycled to Golgi
  4. what is the lysosome involved in?
    digestion of phagoctosed substances and turnover of organelles by autophagy
  5. what is phagocytosis?
    engulf and ingest bacteria by phagosome
  6. what is autophagosome?
    membrane forms bilayer around organelle to autophasome to lysososme to be degraded
  7. what types of pathway are secretory proteins targetted for?
    regulated and consitutive secretion in trans-Golgi
  8. how do secretory granules mature?
    • immature secretory granule buds off
    • gets more dense as it matures: v type ATPase decrease pH allows proteins to condense and concentrate. 
    • Mature granules wait near the plasma for signal, fusion of vesicle and secretion
    • proteins not suppose to be in secretory material sent to sorting endosome
  9. what are the terminal steps in calcium triggered membrane fusion during secretion?
    • tethering/docking
    • ATP-dependent priming
    • Ca sensors: CAP-calcium activating protein for secretion (priming)
    • synaptotagmin-will halt fusion until signal
    • fusion
  10. what are the three pathways to distribute integral membrane proteins to apical or basolateral plasma membrane?
    • direct sorting from TGN (lipid raft)
    • indirect (apical and basal go to basal, then apical go to endosome to lysosome)
    • indirect via transcytosis (both basal and apical go to basal, then apical goes to sorting endosome and apical
  11. what is the function of the Golgi in relation to secretory membrane system?
    • carbohydrate processing
    • protein sorting
    • sphingomylein and glycosphingolipid synthesis
  12. at what phase does the Golgi fragment start to break up? and when does it appear again?
    prophase, cytokinesis
  13. what is the function of microtubles?
    • maintains focused Golgi
    • disruption leads to loss of Golgi and fragmentation
  14. how are proteins transferred through the endomembrane system?
    • transferred in vesicles
    • coat proteins and dynamin drive vesicle formation
    • transmembrane SNARE proteins ensure targeting specificity
    • coats are removed prior to membrane fusion achieve with SNAREs
  15. what does phagocytosis, Clathrin-mediated uptake and Macrophinocytosis need?
    phosphoinositides in endocytic compartments
  16. what are the different mods of endocytosis?
    • macropinocytosis *scoop and engulf
    • Clathrin-coated vesicle
    • non-coated vesicle
    • caveolae *lipid raft areas
    • phagocytosis *engulfmemt

    **Calthrin and cavelao are tightly regulated by recognition of signal
  17. what are the mechanisms of phagocytosis?
    • attachment: recognizes foreign body using protein receptors; actin polymerization
    • engulfment: phagocytic cup uses to engulf bacteria, membrane from endosome allows it to recycle plasma membrane and phagosome matures
    • fusion: with lysosome lower pH to 4-5 (proteosis)
  18. what is the function of actin in the mechanism of phagocytosis?
    • push membrane forward as it forms a cup around bacteria
    • actin is used to push bacteria away from plasma membrane
  19. what is PI (4,5)-P2 important for?
    phagocytosis, clatherin mediated uptake, macrophinocytosis
  20. How do endothelial cells take up nutrients? what are the invaginations in endothelial cells called?
    caveolin, which makes up coat of caveolae, invaginations called little caves
  21. where does caveloin bind and stabilize?
    binds cholestrol and stailizes lipid rafts, immobile in membrane, also uses dynamin
  22. what is the difference between Clarithin and COP vs. caveolin?
    Clathrin and COP gets recruited by adaptor proteins while caveolin is immobile in membrane
  23. what are the protein components of coated vesicles?
    AP2, Clathrin, Dynamin
  24. what is the role of AP2?
    alpha and beta subunits; beta subunit recruits invaginating factors
  25. what is the role of the micro chain on AP2
    it is an adaptor protein that interacts with Clathrin; forms Clathrin cage
  26. how does Clathrin come together?
    the hub connects to two light chains
  27. describe the process of receptor mediated endocytosis by coated vesicles
    • AP2 recruitment (AP2 nd Clathrin)
    • coat assembly and curvature
    • coated pit formation
    • dynamin collar constriction: amphiphysin and dynamin
    • detachment
    • uncoating for transport
  28. what is the role of synaptojanin in receptor mediated endocytosis?
    dephosphorylates PI(4,5)P2 to PI(4)P and the coat falls off
  29. what is the role of amphiphysin in receptor mediated endocytosis?
    interacts with AP2 and recruits dynamin
  30. what does Clathrin coated vesicle formation requires?
    • Cargo receptors
    • adaptins
    • coat proteins
    • dynamin
  31. what does GTPase dynamin provide?
    energy to release vesicles
  32. what is the role of adaptor proteins?
    bind cytoplasmic tails to sort and concentrate
  33. what are the antibodies to the LDLs labeled as?
    ferritin particles
  34. describe the processes of LDLs
    • apolipoprotein binds to receptor
    • binding gets adaptor protein AP2
    • get Clathrin
    • dephosphorylation of PI (4,5)P2 (invagination)
    • vesicles goes to endosome (ph6)--pH change causes receptor to dissociate
  35. why does LDL end up in the lysosome?
    gets chewed up into cholesterol components (spit out for cells to use as free cholesterol)
  36. what is the difference between an early and late endosome?
    EE has pH 6, late endosome pH 5
  37. what is the rate of membrane internalized per minute?
    2-20% of membrane internalized per minute
  38. what is transferrin and is it released at low pHs?
    transferrin binds tightly to iron receptors and is not release when Fe is release, it goes back to membrane with iron receptor
  39. how do endosomal membrane have pH and functional differences?
    different components of different endosomal membranes
  40. describe the process of protein sorting to multivesicular bodies
    • ubiquitylated cargo *Hrs protein added
    • Hrs protein target receptor to ESCRT complexes , which shuttles it to invagination site where it waits for multivesicular body to turn to late endosome
  41. what are some ways viruses and toxins enter into cells?
    • translocation across endosome
    • fusion with endosome
    • lysis of endosome
    • retrograde transport to ER
  42. how do toxins translocate across endosome?
    pH causes conformation change which allows toxins to sweep through
  43. how does toxins fuse through with endosome
    pH change causes viruses to fuse with endosome which allows them to release capsid
  44. how does lysis of endosome occur?
    bacteria poke holes in phagosome and release toxins
  45. what does the retrograde transport of ER entail?
    caveolae; toxins endocytosed to ER and use ER mechanism to get itself back out to cytoplasm