Bio Exam II.3

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Bio Exam II.3
2013-10-04 23:13:26
Cell Bio

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  1. Orientation of Cholesterol Molecules in a Lipid Bilayer. 
    a) Cholesterol molecules are present in both __, but a specific molecule is localized to __.
    • lipid layers in the plasma membranes of most animal cells
    • one of the two layers
  2. Orientation of Cholesterol Molecules in a Lipid Bilayer. 
    b) Each molecule orients itself in the lipid layer such that its __ is close to the __ of a neighboring __ molecule, where it can form a hydrogen bond with the oxygen of the __ between the __ and a __. The __ and __ of the cholesterol molecule interact with adjacent __ of the membrane phospholipids.
    • single hydroxyl group
    • polar head group
    • phospholipid
    • ester group
    • glycerol backbone
    • fatty acid
    • steroid rings
    • hydrocarbon side group
    • hydrocarbon chains
  3. Function and Cell type:
    • supply cholesterol
    • most
  4. Function and Cell type:
    • supplies iron
    • most
  5. Function and Cell type:
    glucose- or mannose-terminal glycoproteins
    • remove injurious agents from circulation (bacteria and viruses)
    • macrophage
  6. Function and Cell type:
    galactose-terminal glycoproteins
    • remove injurious agents from circulation
    • hepatocyte
  7. Function and Cell type:
    IgG immunoglobulins
    • transfer immunity to fetus
    • fetal yolk sac; intestinal epithelial cells of neonatal animals
  8. Function and Cell type:
    • supplies protein to embryo
    • developing oocyte
  9. Function and Cell type:
    • removes injurious agents
    • epithelial cells
  10. Function and Cell type:
    insulin, other peptide hormones
    • alter cellular metabolism; ligand and often receptor are degraded after endocytosis
    • most
  11. Receptor Mediated Endocytosis: (for cholesterol)
    - fate of receptors
    - fate of ligand
    - cholestero
    • receptors recycled
    • ligand broken up
    • cholesterol used by cell membranes
  12. Iron RME
    • carried around by protien, transferrin (only when bound is it called transferrin)
    • end up in a coated vesicle (clathrin)--> uncoat--> fuse with endosome
  13. Iron RME continued:
    - endosome conditions
    -- What does this do?
    - The reaction is __
    - When iron is not bound= __
    • about ph of 5
    • at this pH, iron dissociates from transferrin
    • pH dependent
    • apotransferrin
  14. Explain apotransferrin.
    it is still bound to receptor, even after release of iron. It is recycled back to the membrane, where the pH is about seven, causing transferrin to detach.
  15. In Iron RME, unlike in LDL, what?
    • they don't detach from the membrane once in the endosome. Only on the surface do they detach.
    • pH 7= transferrin dissociates
    • pH 5= iron dissociates
  16. Iron importance?
    cytochrome for mitochondria