膜结构及其转运功能课件

厦门大学医学院 戚 智1Size of the cells2Cell Diversity34一一.细胞膜的分子结构细胞膜的分子结构质膜成分质膜成分 (Composition of Plasma membrane)脂类脂类(Lipid)蛋白质蛋白质(Protein)少量糖类少量糖类(Carbohydrate)5如何用如何用最简单最简单的办法证明细胞膜是单分子层、的办法证明细胞膜是单分子层、双分子层还是多分子层结构？双分子层还是多分子层结构？如果把磷脂分子平铺在水如果把磷脂分子平铺在水面，其分子将如何分布？面，其分子将如何分布？6FLUIDFLUID-because individual phospholipids and proteins can move side-to-side-because individual phospholipids and proteins can move side-to-side within the layer,like its a liquid.within the layer,like its a liquid.MOSAICMOSAIC-because of the pattern produced by the scattered protein molecules-because of the pattern produced by the scattered protein molecules when the membrane is viewed from above.when the membrane is viewed from above.FLUID MOSAIC MODEL(FLUID MOSAIC MODEL(液态镶嵌模型液态镶嵌模型)Thickness 6nmSinger&Nicholson,19727磷脂磷脂Phospholipids Hydrophilic:Hydrophilic:“water loving”Hydrophobic:Hydrophobic:“water fearing”（一）（一）细胞膜的脂质细胞膜的脂质脂质分子种类脂质分子种类:磷脂磷脂(Phospholipid)(Phospholipid)：70%70%胆固醇胆固醇(Cholesterol)(Cholesterol)：30%30%糖脂：糖脂：10%鞘脂鞘脂(Sphingolipids):):少量少量.双嗜性分子（双嗜性分子（Amphipathic molecule）胆固醇8（二）细胞膜的蛋白Membrane ProteinsProteins determine membranes specific functions:Plasma membrane&organelle membranes each have unique collections of proteinsMembrane proteins:peripheral proteins(表面蛋白):reside outside hydrophobic region of lipids,loosely bound to surface of membraneintegral proteins（整合蛋白）:embedded within bilayer,usually across whole membrane transport proteinschannels,permeases(pumps)9（三）细胞膜的糖类（三）细胞膜的糖类Membrane carbohydrates n nPlay a key role in Play a key role in cell-cell-cell recognitioncell recognitionn nability of a cell to ability of a cell to distinguish one cell from distinguish one cell from anotheranothern nantigensantigensn nimportant in organ&important in organ&tissue developmenttissue developmentn nbasis for rejection of basis for rejection of foreign cells by foreign cells by immune systemimmune systemGlycoprotein 糖蛋白Glycolipid 糖脂10二、跨细胞膜的物质转运（一）单纯扩散（一）单纯扩散 Simple diffusion（二）易化扩散（二）易化扩散（Facilitated diffusion）1.经通道易化扩散经通道易化扩散（Facilitated diffusion via ion channel）2.经载体的易化扩散（Facilitated diffusion via carrier）(三三)主动转运主动转运（Active transport）(2）原发性主动转运；Primary active transport(3)继发性主动转运；Secondary active transport12（一）单纯扩散（一）单纯扩散Simple Diffusion-Simple Diffusion-Requires Requires NO NO energyenergy Diffusion is the net movement of Diffusion is the net movement of molecules(or ions)from a region molecules(or ions)from a region of their high concentration to a of their high concentration to a region of their lower region of their lower concentration.concentration.The molecules move down a The molecules move down a concentration gradient.concentration gradient.Molecules have Molecules have kinetic energykinetic energy,which,which makes them move about randomly.makes them move about randomly.As a result of diffusion molecules reach As a result of diffusion molecules reach an an equilibrium equilibrium where they are evenly where they are evenly spread out.This is when there is no net spread out.This is when there is no net movement of molecules from either side.movement of molecules from either side.13141516High speed;(10High speed;(106 610108 8/sec)/sec)Selectivity;Selectivity;GGating.1.1.经通道易化扩散经通道易化扩散(facilitated diffusion via channel)17 GatingGatingGatingGating（门控）（门控）（门控）（门控）:1)Voltage-gated ion 1)Voltage-gated ion 1)Voltage-gated ion 1)Voltage-gated ion channelchannelchannelchannel 2)Chemically-gated ion 2)Chemically-gated ion 2)Chemically-gated ion 2)Chemically-gated ion channelchannelchannelchannel 3)Mechanically-gated 3)Mechanically-gated 3)Mechanically-gated 3)Mechanically-gated ion channelion channelion channelion channel离子通道的门控特性示意图182.经载体易化扩散经载体易化扩散 Facilitated diffusion via carrierGlucose Transporter Glucose Transporter 葡萄糖转运体葡萄糖转运体转运物质转运物质:水溶性水溶性小分子物质小分子物质,如葡萄糖（右旋）、如葡萄糖（右旋）、AA、核苷酸、核苷酸19经载体易化扩散的特点经载体易化扩散的特点经载体易化扩散的特点经载体易化扩散的特点：顺浓度差顺浓度差顺浓度差顺浓度差转运转运转运转运,速度比依溶质物理特性预期的快速度比依溶质物理特性预期的快速度比依溶质物理特性预期的快速度比依溶质物理特性预期的快(move solutes faster move solutes faster across membrane)across membrane);饱和现象饱和现象饱和现象饱和现象(saturation);(saturation);结构特异性结构特异性结构特异性结构特异性(highly specific to specific soluteshighly specific to specific solutes););竞争抑制竞争抑制竞争抑制竞争抑制competitive inhibitioncompetitive inhibition米氏常数米氏常数20（三）主动转运（三）主动转运 active transport定义定义定义定义 细胞膜通过本身某种耗能过程，借助细胞膜某些蛋白质细胞膜通过本身某种耗能过程，借助细胞膜某些蛋白质细胞膜通过本身某种耗能过程，借助细胞膜某些蛋白质细胞膜通过本身某种耗能过程，借助细胞膜某些蛋白质的帮助，将非脂溶性物质分子或离子的帮助，将非脂溶性物质分子或离子的帮助，将非脂溶性物质分子或离子的帮助，将非脂溶性物质分子或离子逆电化学梯度差逆电化学梯度差逆电化学梯度差逆电化学梯度差进行进行进行进行的转运。的转运。的转运。的转运。根据转运能量是否直接来源于根据转运能量是否直接来源于根据转运能量是否直接来源于根据转运能量是否直接来源于ATPATPATPATP的不同分为的不同分为的不同分为的不同分为:原发和继原发和继原发和继原发和继发两种主动转运形式。发两种主动转运形式。发两种主动转运形式。发两种主动转运形式。2121钠泵抑制剂钠泵抑制剂钠泵抑制剂钠泵抑制剂:哇巴因哇巴因哇巴因哇巴因ouabainouabain钠钠-钾泵钾泵 sodium-potassium pump简称钠泵简称钠泵sodium pump,又称又称Na+-K+-ATP酶酶(Na+-K+-ATPase)1.原发性主动转运原发性主动转运 Primary Active Transport22胞内高钾胞内高钾胞内高钾胞内高钾,为代谢提供必需条件为代谢提供必需条件为代谢提供必需条件为代谢提供必需条件（e.g.,e.g.,e.g.,e.g.,核糖体合成蛋白）核糖体合成蛋白）核糖体合成蛋白）核糖体合成蛋白）;维持胞质渗透压和细胞容积的稳定维持胞质渗透压和细胞容积的稳定维持胞质渗透压和细胞容积的稳定维持胞质渗透压和细胞容积的稳定;是细胞产生生物电的前提条件；是细胞产生生物电的前提条件；是细胞产生生物电的前提条件；是细胞产生生物电的前提条件；生电性生电性生电性生电性(排出排出排出排出3Na3Na3Na3Na+,转入转入转入转入2K2K2K2K+)作用作用作用作用,增增增增大膜内负电位大膜内负电位大膜内负电位大膜内负电位,影响静息电位的数影响静息电位的数影响静息电位的数影响静息电位的数值；值；值；值；建立钠的跨膜浓度梯度，为继发性建立钠的跨膜浓度梯度，为继发性建立钠的跨膜浓度梯度，为继发性建立钠的跨膜浓度梯度，为继发性主动转运提供动力（主动转运提供动力（主动转运提供动力（主动转运提供动力（NaNaNaNa+-H-H-H-H+交换，交换，交换，交换，NaNaNaNa+-Ca-Ca-Ca-Ca2+2+2+2+交换）。交换）。交换）。交换）。钠泵（钠钾泵）活动的生理意义钠泵（钠钾泵）活动的生理意义23同向转运体同向转运体（SymporterSymporter）反向转运体反向转运体（AntiporterAntiporter）2.2.继发性主动转运继发性主动转运(secondary active transport)某物质逆差转运某物质逆差转运(主动转运主动转运)所需的能量不直接来自所需的能量不直接来自ATPATP的分解的分解,而而是来自另一物质主动转运形成的势能贮备是来自另一物质主动转运形成的势能贮备(主要是钠泵活动形成的主要是钠泵活动形成的NaNa+在膜两侧的浓度势能差在膜两侧的浓度势能差)。24（1）同向转运）同向转运近端肾小管上皮（Na+-Glucose）小肠黏膜上皮（2Na+-Glucose）Na+-Na+-葡萄糖同向转运体葡萄糖同向转运体葡萄糖同向转运体葡萄糖同向转运体25（1）同向转运）同向转运Na+-氨基酸氨基酸肾小管上皮细胞肾小管上皮细胞肾小管上皮细胞肾小管上皮细胞甲状腺上皮细胞甲状腺上皮细胞26（1）反向转运）反向转运Exchangers(also known as antiporters)are found in many different cells and tissues and perform a variety of important physiological functions.Three examples are shown here.27肠黏膜上皮细胞葡萄糖继发性主动转运模式图肠黏膜上皮细胞葡萄糖继发性主动转运模式图28How about large molecules?Moving large molecules into&out of cell through vesicles消耗能量、主动Exocytosis-出胞=the movement of a substance by a vesicle to the outside of a cell Constitutive Exocytosis-持续性出胞持续性出胞 Regulated Exocytosis-调节性出胞调节性出胞 endocytosis 入胞=the movement of a substance into a cell by a vesicle phagocytosis 吞噬=“cellular eating”Pinocytosis-吞饮=“cellular drinking”（四）膜泡运输（Vesicular transport）29301.出胞出胞（Exocytosis)Large molecules that are manufactured in the Large molecules that are manufactured in the cell are released through the cell membranecell are released through the cell membrane.Inside CellCell environment3031ExocytosisExocytic Exocytic vesicle vesicle immediately immediately after fusion after fusion with plasma with plasma membrane.membrane.copyright cmassengale31Exocytosis:regulated and constitutive secretion.During secretion,vesicles derived from the trans face of the Golgi complex will fuse with the plasma membrane,dumping their contents into the extracellular environment.In constitutive secretion,secretory vesicles are continuously delivered to the plasma membrane,where they rapidly fuse with the membrane.In regulated secretion,the vesicles derived from the trans face of the Golgi complex aggregate and concentrate their contents in the cytoplasm,where they remain until the cell has received the appropriate signal.Then,the secretory vesicles fuse with the plasma membrane.The contents of these two classes of secretory vesicles are distinct.（1）持续性出胞）持续性出胞 Constitutive Exocytosis（2）调节性出胞）调节性出胞 Regulated Exocytosis例：小肠黏膜杯状细胞分泌黏液例：小肠黏膜杯状细胞分泌黏液例：动作电位达到神经末梢引起神经递质的释放例：动作电位达到神经末梢引起神经递质的释放32（1）Phagocytosis（吞噬）（吞噬）Used to Used to engulf large engulf large particlesparticles such as such as bacteriabacteria,etc.into vesiclesetc.into vesicles(Cell eating)2.入胞（入胞（Endocytosis）3334Phagocytosis About to OccurPhagocytosis About to Occurcopyright cmassengale34Cell forms an Cell forms an invaginationinvaginationMaterials Materials dissolve in waterdissolve in water to be brought into cell to be brought into cellCalled Called“Cell Drinking”“Cell Drinking”（2）吞饮）吞饮(Pinocytosis)3536受体介导的入胞受体介导的入胞Receptor-mediated endocytosis3738液态镶嵌模型液态镶嵌模型双噬性分子双噬性分子磷脂磷脂胆固醇胆固醇表面蛋白表面蛋白整合蛋白整合蛋白单纯扩散单纯扩散易化扩散易化扩散离子通道离子通道离子选择性离子选择性化学门控通道化学门控通道电压门控通道电压门控通道机械门控通道机械门控通道水通道水通道外语要求外语要求Fluid mosaic modelFluid mosaic modelAmphipathic moleculeAmphipathic moleculePhospholipidPhospholipidCholesterolCholesterolPeripheral proteinPeripheral proteinIntegral proteinIntegral proteinSimple diffusionSimple diffusionFacilitated diffusionFacilitated diffusionIon channelIon channelIon selectivityIon selectivityChemically-gated ion channelChemically-gated ion channelVoltage-gated ion channelVoltage-gated ion channelMechanically-gated ion channelMechanically-gated ion channelWater channelWater channel39转运体转运体载体载体主动转运主动转运钠钠-钾泵钾泵钙泵钙泵被动转运被动转运继发性主动转运继发性主动转运同向转运体同向转运体反向转运体反向转运体交换体交换体膜胞转运膜胞转运出胞出胞入胞入胞吞噬吞噬吞饮吞饮受体介导入胞受体介导入胞Transporter Transporter CarrierCarrierActive transportActive transportSodium-potassium pumpSodium-potassium pumpCalcium pumpCalcium pumpPassive transportPassive transportSecondary active transportSecondary active transportSymporterSymporterAntiporterAntiporterExchangerExchangerVesicular transportVesicular transportExocytosisExocytosisEndocytosisEndocytosisPhagocytosisPhagocytosisPinocytosisPinocytosisReceptor-mediated endocytosis Receptor-mediated endocytosis 40个人观点供参考，欢迎讨论！