BIOL 118 Lecture 6: CHAPTER 6 PART 2
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13 Feb 2017
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Linked to a small, organic molecule that is polar or charged. Two fatty acids or two isoprene chains: organic molecule bound to the phosphate group. And a nonpolar hydrophobic region: some steroids are amphipathic. In water(figure 6. 5: phospholipids spontaneously form micelles or lipid bilayers, the polar phosphate heads face outward, and the hydrophobic fatty acid tails face inward toward other tails. Artificial membranes: vesicles can form from phospholipids in the lab. Artificial membrane bound vesicles are called liposomes. Phospholipid bilayers (figure 6. 8: are highly selective in what can cross them, small of nonpolar molecules move across phospholipid bilayers easily. Water, glycerol (small uncharged polar: charged or large polar substances cross slowly or not at all. Ions (highly charged: phospholipid bilayers have selective permeability. Does the type of lipid in the membrane affect its permeability: membrane permeability is affected by: Bilayers with unsaturated hydrocarbons and/or shorter hydrocarbon tails (figure. Bilayers with saturated hydrocarbons and/or longer tails.