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1、FacilitateciIliffusionandActiveTransportFacilitatedDiffusionMovementofspecificmoleculesacrosscellmembranesthroughproteinchannelsIEachproteinchannelonlyallowsaparticularsubstancestocrossTheproteinfacilitates(helps)thediffusionacrossthemembraneOccurswiththefollowing:1.Chargedmolecules(ions)2.Whenmolec
2、ulesaretoolargeAlthoughfacilitateddiffusionisfastandspecific,itisstilldiffusion.HNetmovementofmoleculesacrossamembraneoccursfromthesidewithahigherconcentrationlowerconcentrationside.Doesnotrequireenergy.AftiveTransoortActiveTransportenergy-requiringprocessthatmovesmaterialacrossacellmembraneagainsta
3、concentrationdifferencei9=energyusedinactivetransportActiveTransportMovematerialsintheoppositedirectionagainstaconcentrationdifferenceRequires:1energy+HIGH+2.transportproteinsExamplesfActiveTransport1. Endocytosis2. ExocytosisMolecularTransport(useofproteinsorproteinchannels)EndocHosisProcessbywhich
4、acelltakesmaterialintothecellbyinfoldingsorpocketsofthecellmembrane.HBTransports:Largermolecules2.SolidclumpsofmaterialenergyPhagocytosis-“cellPhagocytosis一whenextensionsofthecytoplasmsurroundparticles,packageitwithinafoodvacuole,thencellengulfsitiTheprocessofengulfingtakesaLOTofScanningelectronmicr
5、ographofaphagocyte(yellow,right)phagocytosinganthraxbacilli(orange,left)PinocytoslsucelldrinkingJustlikeendocytosis;processwherecellstakeupliquidfromthesurroundingVesicleenvironment,fusewithmembrane，andreleasethesefluidfilledvacuoleswithinthecell.ExocytosisExocytosisl-Processbywhichacellreleaseslarg
6、eamountsofmaterial.VacuolefuseswithcellmembraneTransports:Largermolecules2.SolidclumpsofmaterialMolecularTransportNa/KPump(Sodium/PotassiumPump)CellscontainhighamountsofKinsidethecellandhighamountsofNaoutsidethecelland，inordertomaintaincellvolumeandrestingcellpotential,thispumpgetsused.highered.mcgraw-hill/sites/0072495855/student_view0/chapter2/animation_how_the_sodium_potassium_pump_works.html
