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Unformatted text preview: www.youtube.com/watch?v=ULR79TiUj80&feature=related Membranes function as selective chemical barriers- Membrane permeability Phospholipids are amphiphilic moleculesHydrophilic and hydrophobic molecules interact differently with water … Chemical nature of phospholipidsPhosphatidylcholine Lipids assemble spontaneously into sheets, liposomes and micellesLipids self-associate without covalent bonding; their tails cooperate to exclude water
A lipid’s chemistry determines its geometric shape (e.g. cones, cylinder, etc.) Different kinds of phospholipids- * Note their asymmetric distribution in the two membrane leaflets Diffusion freedom of lipids in the plane of the membraneLateral and rotational lipid movement Lipids can associate to form rafts Demonstrate using FRAP of lipids with attached fluorophores Membrane fluidity and appearance depends on its phospholipid compositionMembrane thickness Cholesterol affects membrane fluidity and decreases permeability Membrane fluidity is affected by temperature and degree of lipid saturationNon-physiological physiological melting Biosynthesis of lipids in one side of the ER membraneEndoplasmic reticulum cytosolic face membrane lumen Transport of lipidsWithin a membrane Between membranes
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