CH07_2_ - Plasma Membrane Molecular structure of lipids...

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Unformatted text preview: Plasma Membrane Molecular structure of lipids hydrophobic tail tail hydrophilic head Phospholipid bilayer hydrophobic region hydrophilic region region held together by hydrophobic interactions Plasma Membrane Fluid mosaic model phospholipid bilyer = fluid bilyer fluid protein molecules embedded hydrophobic part of protein in hydrophobic part of bilayer hydrophilic part of protein in hydrophilic part of protein in hydrophilic hydrophilic part of bilayer Bio 230, Summer 2010, Ch 7, Page 1 FluidFluid-Mosaic Model Fig. 7-3 PO4-Lipid Movements Fig. 7-5a Bio 230, Summer 2010, Ch 7, Page 2 Plasma Membrane Fluidity phospholipids move rapidly, 2 phospholipids move rapidly m/sec proteins drift more slowly cholesterol stabilizes the membrane making it less fluid membrane making it less fluid Membrane Fluidity Fig. 7-5b Bio 230, Summer 2010, Ch 7, Page 3 Cholesterol Fig. 7-5c Fig. 5-15 Cholesterol Fig. 7-5c Bio 230, Summer 2010, Ch 7, Page 4 Plasma Membrane Fig. 7-7 (animal cell) Membrane proteins have functions Collagen Mutations Can create hyperstretchy skin Bio 230, Summer 2010, Ch 7, Page 5 Muscular Dystrophy Cause: Mutation in large cytoskeletal protein (dystrophin) cytoskeletal protein (dystrophin) that that stabilizes plasma membrane during muscle contractions. Repeated contractions cause muscle fiber death muscle fiber death. Transmembrane Proteins Fig. 7-8 1. Proteins determine function of membrane 2. Integral proteins = transmembrane proteins -hydrophobic regions have nonpolar amino acids 3. Example: integrin -associated w/ microfilaments & ECM proteins 4. Peripheral proteins bound to surface Bio 230, Summer 2010, Ch 7, Page 6 Functions of Membrane Proteins Fig. 7-9a-c Functions of Membrane Proteins Fig. 7-9d-f Bio 230, Summer 2010, Ch 7, Page 7 Diffusion The spontaneous tendency The of a substance to move down its concentration gradient from a more concentrated to a less concentrated area less Osmosis The diffusion of water across across a selectively permeable membrane. Solutes may or may not also diffuse, diffuse, depending on circumstances Bio 230, Summer 2010, Ch 7, Page 8 Diffusion of Solute Across Membrane GC2->C1 = RT ln (C1/C2) 10x Conc Diff = 1.37 kcal/mole C2 C1 Fig. 7-11a Diffusion of Two Solutes Across Membrane Fig. 7-11b Bio 230, Summer 2010, Ch 7, Page 9 Osmosis Hypotonic = less than (<) Fig. 7-12a Hypertonic = more than (>) Pressure pushes some water to other side. Osmotic Pressure Selectively permeable membranes allow only water to diffuse A bit more dilute A bit more concentrated Osmosis Fig. 7-12b Selectively permeable membranes allow only water to diffuse to diffuse Bio 230, Summer 2010, Ch 7, Page 10 Osmosis & Water Balance = Fig. 7-13 wilted -hydrophobic molecules -O2, CO2 -H2O and ethanol Channel Carrier Pump Fig. 7-17 -no energy required -with concentration gradient -energy required -against concentration gradient Bio 230, Summer 2010, Ch 7, Page 11 Ion Channel Fig. 7-15a Carrier Fig. 7-15b Bio 230, Summer 2010, Ch 7, Page 12 Electrogenic Pump Fig. 7-18 Fig. 7-16 Na/K Pump Bio 230, Summer 2010, Ch 7, Page 13 Fig. 7-16 Na/K Pump CoCo-transport Fig. 7-19 Bio 230, Summer 2010, Ch 7, Page 14 Endocytosis Fig. 7-20a Phagocytosis Endocytosis Fig. 7-20b Pinocytosis Bio 230, Summer 2010, Ch 7, Page 15 Endocytosis Fig. 7-20c ReceptorReceptor-Mediated Endocytosis Familial Hypercholesterolemia Cause: Due to mutation in LDL receptor, receptor, cholesterol cannot be taken up from plasma into cells by receptorreceptor-mediated endocytosis. This creates very high plasma This creates very high plasma cholesterol cholesterol concentration and resulting atherosclerosis. Bio 230, Summer 2010, Ch 7, Page 16 ...
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This note was uploaded on 11/28/2011 for the course BIOL 230 taught by Professor J.breckler during the Spring '11 term at S.F. State.

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