SchoolofLifeScienceSchoolofLifeScienceandBiotechnology,Lecture3-MicrobialcellChapter4BROCKBIOLOGYOFCollegeofLifeScienceandShanghaiJiaoTongUniversity 交通大學(xué)生命科學(xué)與技術(shù)學(xué)SchoolofLifeScienceandBiotechnology,3.4CellMorphologyandSignificanceofBeingMajorBacterialCellCoccus(plural,cocci)Spirillum(plural,spirilla)AppendagedbacteriaFilamentousbacteria交通大學(xué)生命科學(xué)與技術(shù)學(xué)SchoolofLifeScienceandBiotechnology,ThesizeofmicrobialProkaryotesvarydramaticallyinbothsizeandvolumefromcellssmallerthan0.2mindiametertothosemorethan50mindiameter.Mostverylargeprokaryotesareeithersulfurchemolithotrophsorcyanobacteria.多數(shù)大型的ShanghaiJiaoTong交通大學(xué)生命科學(xué)與技術(shù)學(xué)SchoolofLifeScienceandBiotechnology,Nutrientsandwasteproductspassmorereadilyintoandoutofasmallcell,thusacceleratingcellularmetabolismandgrowth營(yíng)養(yǎng)物和代謝Reason:surface-to-volume(S/V)ShanghaiJiaoTongRelativetocellvolume,smallcellscontainsurfaceareathandolargecells:highersurface-to-volume(S/V)ratio 交通大學(xué)生命科學(xué)與技術(shù)學(xué)SchoolofLifeScienceandBiotechnology,Perunitofavailableresources,smallcellswilltypicallydeveloplargerpopulationslargercellpopulationsmeanmorecellmoremutationsaccumulatefromspontaneouserrorsinDNAreplicationmutationsare‘rowmaterial’thatevolutionaryShanghaiJiaoTong交通大學(xué)生命科學(xué)與技術(shù)學(xué)SchoolofLifeScienceandBiotechnology,II.CellMembrancesandCellCytoplasmicmembranes:Cytoplasmicmembranes:MembranetransportCellTheOuterMembranceofGram-negativeShanghaiJiaoTongSchoolofLifeScienceSchoolofLifeScienceandBiotechnology,3.5CytoplasmicHowcellscollectanduptakenutrientsfromtheenvironment?p.66section交通大學(xué)生命科學(xué)與技術(shù)學(xué)SchoolofLifeScienceandBiotechnology,Cytoplasmicmembraneathinstructurethatcomple ysurroundsthePhysicalbarrierseparatinginsideofacellfromitsoutsideenvironment.是細(xì)胞的物理屏障Highlyselectivepermeabilitybarrierenablingacelltoconcentratespecificmetabolitesandexcretewastematerials是細(xì)胞吸收營(yíng)養(yǎng)物或排出廢物的選ShanghaiJiaoTong交通大學(xué)生命科學(xué)與技術(shù)學(xué)SchoolofLifeScienceandBiotechnology,Phospholipidbilayer-8nmOccursinBacteriaandEukarya,notinStructure:Glycerolbackboneattachedwithfattyacidsandphosphate-containinggroupsbyesterlinkage結(jié)構(gòu)甘油骨架以酯鍵連接脂肪酸與磷酸.enlargedschematicviewofasingleunitelectronmicrographofphotosyntheticmembranestacksderivedfromthecytoplamicmembraneinaphototrophicbacteriumThecytoplasmicSchoolofLifeScienceSchoolofLifeScienceandBiotechnology,MembraneFluid流動(dòng)鑲Fluidmosaics(1)流動(dòng)ThematrixoftheunitmembraneisThematrixoftheunitmembraneiscomposedofphospholipids,withthehydrophobicgroupsdirectedinwardandthehydrophilicgroupstowardtheoutside,wheretheyassociatewithwater.DiagramofthestructureofthecytoplasmicFluidmosaics(2)流動(dòng)EmbeddedEmbeddedinthematrixareproteinsthathaveconsiderablehydrophobiccharacterintheregionthattraversesthefattyacidbilayer.Hydrophilicproteinsandotherchargedsubstances,suchasmetalions,maybeattachedtothehydrophilic.Diagramofthestructureofthecytoplasmic交通大學(xué)生命科學(xué)與技術(shù)學(xué)SchoolofLifeScienceandBiotechnology,Fluidmosaics(3)流動(dòng)鑲Althoughappearingsomewhatrigid,thecytoplasmicmembraneisactuallyquitefluid;phospholipidandproteinmoleculeshavesignificantfreedomtomoveaboutthemembranesurface.Thus,membranescanbethoughtofShanghaiJiaoTong交通大學(xué)生命科學(xué)與技術(shù)學(xué)SchoolofLifeScienceandBiotechnology,3.5.3MembranestrengtheningAgentsSterolsandHopanoids固醇與藿烷類化合物TheeukayoteshavesterolsintheirSterolsareabsentfromthemembranesofvirtuallyallprokaryotes(exceptmethanotrophicbacteriaandthemycoplasmas)原核生物細(xì)胞Dependingonthecelltype,sterolscanmakeupfrom5to25%ofthetotallipidsofeukaryoticmembranes.固醇可達(dá)到真核細(xì)胞膜總脂量的5-ShanghaiJiaoTong交通大學(xué)生命科學(xué)與技術(shù)學(xué)SchoolofLifeScienceandBiotechnology,SterolsandHopanoids:Sterolsservestostabilizeitsstructureandmakeitlessflexible.(Sterolsarerigid,planarmoleculeswhereasfattyacidsareflexible.固醇:穩(wěn)定膜的結(jié)構(gòu),減少細(xì)胞膜柔性.Hopanoidsaremoleculessimilartosterols,theypresentinthemembranesofmanyBacteriamayplayarolesimilartothatofsterolsineukaryoticcells.藿烷類化合物的作用與固醇可能相似ShanghaiJiaoTong交通大學(xué)生命科學(xué)與技術(shù)學(xué)SchoolofLifeScienceandBiotechnology,3.5.4DifferencesofmembranestructureAchaealThelipidsinBacteriaandEukarya:fattyacidslinkedwithglycerolmoleculesbyesterlinkages.細(xì)菌/真核:酯鍵連接脂肪酸與甘油LipidsfromArchaea:haveetherlinkagesbetweenglycerolandtheirhydrophobicsidechains.古生菌:醚鍵連接疏水側(cè)鏈與甘油Inaddition,archaealipidslackfattyacidsandinsteadhavesidechainscomposedofrepeatingunitsofthefive-carbonhydrocarbonShanghaiJiaoTongChemicalbondsin(b)(b)Theetherlinkageoflipidsfrom(a)TheesterlinkageasfoundinthelipidsofBacteriaand(c)Isoprene異戊二烯,theparentstructureofthehydrophobicsidechains(R)ofarchaeallipids.Bycontrast,inlipidsofBacteriaandEukarya,Rarefattyacids.of4linkedisoprenesGlyceroldiethersanddiglyceroltetraethersarethemajorclassesoflipidspresentinArchaea.Inthetetraethermoleculethephytanyl(composedof4linkedisoprenes)sidechainsfromeachglycerolmoleculearecovalentlyMembranestructureinArchaea:LipidbilayerandlipidDietheryieldsbilayer,whileTetraetheryieldsalipidmonolayerinsteadofalipidbilayerMonolayermembraneisquiteresistanttopeelingapart.甘油二醚形成脂雙層,而二甘油四醚導(dǎo)致脂單層MonolayerWidespreadamonghyperthermophilicAchaea脂單交通大學(xué)生命科學(xué)與技術(shù)學(xué)SchoolofLifeScienceandBiotechnology,DifferencesofmembranestructurebetweenAchaeaandBacteriaside sidechainngagent FattyFattyShanghaiJiaoTong交通大學(xué)生命科學(xué)與技術(shù)學(xué)SchoolofLifeScienceandBiotechnology,3.6CytoplasmicMembrane:PermeabilitybarrierPreventpassiveProteinanchorEnergyconservationProtonmotiveforceforATPgeneration產(chǎn)生ATPShanghaiJiaoTongNecessityforTransportSimplediffusionisnotenoughforcellfunctions簡(jiǎn)SimplediffusioncannotoccuragainstgradientNutrientconcentrationoutofcellistoolowisnecessary載體UptakeofnutrientscanoccuragainstconcentrationgradienttheratethuscanbeconstantandNumberandtypeofcarriersregulatedby

Relationshipbetweenuptakerateandexternalconcentrationindiffusionand交通大學(xué)生命科學(xué)與技術(shù)學(xué)holofifScend, 系

rtThereareatleastthreeclassesofmembrane-transportingsystems:三種膜 SimpletransportGrouptranslocationABCsystem(ATP-bindingcassetteABCShanghaiJiaoTong :involvingonlyone基團(tuán)轉(zhuǎn)運(yùn)involvingaperiplasmic-bindingcomponentplusaABC系統(tǒng):involvingaseriesofproteinsthatcooperatetomediatethetransportevent交通大學(xué)生命科學(xué)與技術(shù)學(xué)SchoolofLifeScienceandBiotechnology,transporters穿膜 Inprokaryotes,membrane-spanningtransporterstypicallycontain12alphahelicesthatalignwitheachotherinacircletoformachannelthroughthemembrane.原核生物的穿膜 Uniportersareproteinsthatsimplytransportamoleculeinaunidirectionalfashionacrossthemembrane單向蛋白Threeindividualtransporters,eachshowingadifferenttypeoftransporteventThecotransportedmoleculeisshowninyellow.有三種蛋白,協(xié)同分子為黃色Antiportersareproteinsthattransportasubstanceacrossthemembraneinonedirectionwhileasecondsubstanceintheopposite蛋白Threeindividualtransporters,eachshowingadifferenttypeoftransporteventThecotransportedmoleculeisshowninyellow.有三種蛋白,協(xié)同分子為黃色SymportersareproteinsthattransportasubstancealongwithanotherfrequentlyaprotonSymportersareproteinsthattransportasubstancealongwithanotherfrequentlyaprotonThreeindividualtransporters,eachshowingadifferenttypeoftransporteventThecotransportedmoleculeisshowninyellow.有三種蛋白,協(xié)同分子為黃色交通大學(xué)生命科學(xué)與技術(shù)學(xué)SchoolofLifeScienceandBiotechnology,Symporter:LacpermeaseRelyonprotonmotiveforceforOneprotonneededforeachlactosetakenintocell每Doesnotmodifysubstance(lactoseduring ShanghaiJiaoTong交通大學(xué)生命科學(xué)與技術(shù)學(xué)SchoolofLifeScienceandBiotechnology,Atransportprocessinwhichthetransportedsubstanceischemicallyalteredduringpassageacrossthemembrane.底物在 Example:Phosphotransferasesystemforsugarsuptake磷酸轉(zhuǎn)移酶系統(tǒng)ShanghaiJiaoTongMechanismofthephosphotransferase Forglucoseuptake,thesystemconsistsof5proteins.Sequentialp