细胞质膜与细胞表面讲义_Cell_Membrane_and_Cell_Surfa

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1、CellMembraneandCellSurfaceI.CellMembraneII.CellJunctionsIII.CellAdhesionIV.ExtracellularMatrixhttp://www.cbi.pku.edu.cn/chinese/documents/chenjg/I.Biomembranes:TheirStructure,ChemistryandFunctionsLearningobjectives:AbriefhistoryofstudiesonthestructrureoftheplasmamembraneModelofmembranestructure:an

2、experimentalperspectiveThechemicalcompositionofmembranesCharacteristicsofbiomembraneAnoverviewofthefunctionsofbiomembranes1.AbriefhistoryofstudiesonthestructrureoftheplasmicmembraneA.Conception:Plasmamembrane(cellmembrane),Intracellularmembrane,Biomembrane.B.ThehistoryofstudyOverton(1890s):Lipidn

3、atureofPM;J.D.Robertson(1959):TheTEMshowing:thetrilaminarappearanceofPM;Unitmembranemodel;S.J.SingerandG.Nicolson(1972):fluid-mosaicmodel;K.Simonsetal(1997):lipidraftsmodel;FunctionalraftsinCellmembranes.Nature387:569-5722.SingerandNicolson’sModelofmembranestructure:Thefluid-mosaicmodelisthe“ce

4、ntraldogma”ofmembranebiology.Thecorelipidbilayerexistsinafluidstate,capableofdynamicmovement.Membraneproteinsformamosaicofparticlespenetratingthelipidtovaryingdegrees.TheFluidMosaicModel,proposedin1972bySingerandNicolson,hadtwokeyfeatures,bothimpliedinitsname.3.ThechemicalcompositionofmembranesA.M

5、embraneLipids:TheFluidPartoftheModelPhospholipids:PhosphoglycerideandsphingolipidsGlycolipidsSterols(isonlyfoundinanimals)Membranelipidsareamphipathic.Therearethreemajorclassesoflipids:Figure10-2.Thepartsofaphospholipidmolecule.Phosphatidylcholine,representedschematically(A),informula(B),asaspace-

6、fillingmodel(C),andasasymbol(D).Thekinkduetothecis-doublebondisexaggeratedinthesedrawingsforemphasis.Figure10-3.Alipidmicelleandalipidbilayerseenincross-section.Lipidmoleculesformsuchstructuresspontaneouslyinwater.Theshapeofthelipidmoleculedetermineswhichofthesestructuresisformed.Wedge-shapedlipid

7、molecules(above)formmicelles,whereascylinder-shapedphospholipidmolecules(below)formbilayers.Figure10-4.Liposomes.(A)Anelectronmicrographofunfixed,unstainedphospholipidvesicles(liposomes)inwater.Thebilayerstructur