《细胞膜和细胞表面》PPT课件

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1、细胞膜与细胞表面plasmamembraneandcellsurface膜脂LipidCompositionandStructuralOrganization生物膜的结构基础，脂质双分子层Biomembranes:LipidCompositionandStructuralOrganization膜脂——生物膜的基本组成成分ThreeClassesofLipidsAreFoundinBiomembranes膜脂可分为三大类，磷脂（磷脂甘油），鞘脂和胆固醇Atypicalbiomembraneisassembledfromphosphog

2、lycerides,sphingolipids,andsteroids.Allthreeclassesoflipidsareamphipathicmoleculeshavingapolar(hydrophilic)headgroupandhydrophobictail.磷脂甘油3-磷酸甘油的衍生物themostabundantclassoflipidsinmostmembranes,arederivativesofglycerol3-phosphate.磷脂具有2个脂酰基构成的疏水性尾部和与磷酸相连的亲水性头部Atypicalphosp

3、hoglyceridemoleculeconsistsofahydrophobictailcomposedoftwofattyacylchainsesterifiedtothetwohydroxylgroupsinglycerolphosphateandapolarheadgroupattachedtothephosphategroup.Phosphatidylethanolamine磷脂酰乙醇胺Phosphatidylcholine磷脂酰胆碱Phosphatidylserine磷脂酰丝氨酸Phosphatidylinositol磷脂酰

4、肌醇红色部分为鞘氨醇，具有一个长的碳氢链，一个氨基与脂肪酸链相连，一个羟基和磷酸相连Allofthesecompoundsarederivedfromsphingosine,anaminoalcoholwithalonghydrocarbonchain,andcontainalong-chainfattyacidattachedtothesphingosineaminogroup.sphingomyelins鞘磷脂Glucosylcerebroside，葡萄糖神经酰胺，是一种糖脂，糖脂在神经组织最多Glycolipidsconstitu

5、te2–10percentofthetotallipidinplasmamembranes;theyaremostabundantinnervoustissue.胆固醇，有4个环，一个羟基（亲水）前面两种膜脂可以单独或混合形成脂双层，胆固醇则不能形成脂双层。Cholesterolisespeciallyabundantintheplasmamembranesofmammaliancellsbutisabsentfrommostprokaryoticcells.Asmuchas30–50percentofthelipidsinplantp

6、lasmamembranesconsistofcertainsteroidsuniquetoplants.膜脂在细胞质侧和外侧的分布不一样MembraneLipidsAreUsuallyDistributedUnequallyintheExoplasmicandCytosolicLeaflets在红细胞，鞘脂和磷脂胆碱，分布细胞外侧，磷脂乙醇胺，磷脂丝氨酸，磷脂肌醇，分布在细胞内侧inplasmamembranesfromhumanerythrocytes,almostallthesphingomyelinandphosphatidyl

7、choline,bothofwhichformlessfluidbilayers,arefoundintheexoplasmicleaflet.Incontrast,phosphatidylethanolamine,phosphatidylserine,andphosphatidylinositol,whichformmorefluidbilayers,arepreferentiallylocatedinthecytosolicleaflet.脂双层结构的形成thepolarheadgroupsinallphospholipidscan

8、packtogetherintothecharacteristicbilayerstructure.Sphingomyelinsaresimilarinshapetophosphoglyceridesand