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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
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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
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Function and Cell type:
LDL
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Function and Cell type:
transferrin
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Function and Cell type:
glucose- or mannose-terminal glycoproteins
- remove injurious agents from circulation (bacteria and viruses)
- macrophage
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Function and Cell type:
galactose-terminal glycoproteins
- remove injurious agents from circulation
- hepatocyte
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Function and Cell type:
IgG immunoglobulins
- transfer immunity to fetus
- fetal yolk sac; intestinal epithelial cells of neonatal animals
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Function and Cell type:
phosphovitellogenins
- supplies protein to embryo
- developing oocyte
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Function and Cell type:
fibrin
- removes injurious agents
- epithelial cells
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Function and Cell type:
insulin, other peptide hormones
- alter cellular metabolism; ligand and often receptor are degraded after endocytosis
- most
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Receptor Mediated Endocytosis: (for cholesterol)
- fate of receptors
- fate of ligand
- cholestero
- receptors recycled
- ligand broken up
- cholesterol used by cell membranes
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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
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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
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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.
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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
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Iron importance?
cytochrome for mitochondria
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