華中農(nóng)業(yè)大學(xué)微生物學(xué)第二章演示文稿

華中農(nóng)業(yè)大學(xué)微生物學(xué)第二章演示文稿現(xiàn)在是1頁(yè)\一共有91頁(yè)\編輯于星期三

2.1Overviewofthestructureofmicrobialcells2.2Procaryoticcellwall2.3Cytoplasmicmembrane2.4Cellulargeneticinformation2.5Cytoplasmicmatrix–RibosomeandInclusions2.6Componentsexternaltothecellwall2.7Bacterialendospores2.8ComparisonoftheprokaryoticandeukaryoticcellChapterOutline現(xiàn)在是2頁(yè)\一共有91頁(yè)\編輯于星期三ConceptsProkaryotesaresmallandsimpleinstructurewhencomparedwitheukaryotes,yettheyoftenhavecharacteristicshapeandsize.

Prokaryoticgeneticmaterialislocatedinanareacalledthenucleoidandisnotenclosedbyamembrane.Theprokaryoticcellwallalmostalwayshaspeptidoglycanandischemicallyandmorphologicallycomplex.現(xiàn)在是3頁(yè)\一共有91頁(yè)\編輯于星期三AprocaryoticcellAeucaryoticcell2.1OverviewofCellStructure現(xiàn)在是4頁(yè)\一共有91頁(yè)\編輯于星期三3.TheircellwallalmostalwayscontainthecomplexpolysaccharidepeptidoglycanTheProkaryoticCell1.Theirgeneticmaterial(DNA)isnotenclosedwithinamembraneandtheylackothermembrane–boundedorganelles2.TheirDNAisnotassociatedwithhistidine4.Theyareverysmall!!現(xiàn)在是5頁(yè)\一共有91頁(yè)\編輯于星期三Schematicdiagramofabacterialcell現(xiàn)在是6頁(yè)\一共有91頁(yè)\編輯于星期三Size:

Mostbacteriafallwithinarangefrom0.2to2.0umindiameterandfrom2to8uminlengthArod-shapedprokaryoteistypicallyabout1-5micrometers(μm)longandabout1μmwideMicroorganismsingeneralareverysmallandarecompletelyinvisibletothenakedeye.Acyanobacterium8x50um現(xiàn)在是7頁(yè)\一共有91頁(yè)\編輯于星期三sizecomparisonofmicroorganismsVisibilityscaleMetersRelativesizeofMicrobesProkaryotesEukaryotesVirusesNakedeyeLightmicroscopeElectronmicroscope現(xiàn)在是8頁(yè)\一共有91頁(yè)\編輯于星期三acellincreasesinsize,itssurfacearea–to–volumeratiodecreasesSurfaceareaandvolumerelationshipsincells現(xiàn)在是9頁(yè)\一共有91頁(yè)\編輯于星期三spirallumShape:BacteriahaveafewbasicshapessphericalcoccusRod-shapedbacillus現(xiàn)在是10頁(yè)\一共有91頁(yè)\編輯于星期三2.2ProkaryoticCellWallCellWall現(xiàn)在是11頁(yè)\一共有91頁(yè)\編輯于星期三Thecellwallofthebacterialcellisacomplex,semi-rigidstructurethatisresponsibleforthecharacteristicshapeofthecell.Thecellwallsurroundstheunderlying,fragileplasma(cytoplasmic)membraneandprotectsitandinternalpartsofthecellfromadversechangesinthesurroundingenvironment.Almostallprokaryoteshavecellwalls.現(xiàn)在是12頁(yè)\一共有91頁(yè)\編輯于星期三Gram+Gram-SchematicdiagramofbacterialcellwallsBacteriacanbedividedintotwomajorgroups,calledgram-positiveandgram-negative.Theoriginaldistinctionbetweengram-positiveandgram-negativewasbasedonaspecialstainingprocedure,theGramstain現(xiàn)在是13頁(yè)\一共有91頁(yè)\編輯于星期三TheGram-positivecellwallhasapeptidoglycanlayerthatisrelativelythick(ca.40nm)andcomprisesapproximately90%ofthecellwall.ThecellwallsofmostGram-positiveeubacteriaalsohaveteichoicacids.Gram-positiveCellWall現(xiàn)在是14頁(yè)\一共有91頁(yè)\編輯于星期三StructureoftheRepeatingUnitinPeptidoglycanTheseconstituentsareconnectedtoformarepeatingstructure,theglycantetrapeptide.Peptidoglycaniscomposedoftwosugarderivatives,N-acetylglucosamine(NAG)andN-acetylmuramicacid(NAM),andasmallgroupofaminoacidsconsistingofL-alanine,D-alanine,D-glutamicacid,andeitherlysineordiaminopimelicacid(DAP).現(xiàn)在是15頁(yè)\一共有91頁(yè)\編輯于星期三現(xiàn)在是16頁(yè)\一共有91頁(yè)\編輯于星期三Peptideandglycanunitsareconnectedinformationofthepeptidoglycansheet現(xiàn)在是17頁(yè)\一共有91頁(yè)\編輯于星期三Gram-positiveBacteriafrequentlyhaveacidicpolysaccharidescalledteichoicacidsattachedtotheircellwall.Thetermteichoicacidsincludesallwall,membrane,orcapsularpolymerscontainingglycerophosphateorribitolphosphateresidues.ThesepolyalcoholsareconnectedbyphosphateestersandusuallyhaveothersugarsandD-alanineattached.

TeichoicAcids現(xiàn)在是18頁(yè)\一共有91頁(yè)\編輯于星期三Teichoicacidsandlipoteichoicacidsarearrangedintheoverallwallstructureofgram-positiveBacteria.TeichoicacidLipoteichoicacid現(xiàn)在是19頁(yè)\一共有91頁(yè)\編輯于星期三TheGram-negativecellwallisathinlayerattachedtoanoutermembranevialipoproteins.Theoutermembranecontainsphospholipidonitsinnersurfaceandlipopolysaccharide(LPS)onitsoutersurface.Thespacebetweentheoutermembraneandthecytoplasmicmembraneiscalledtheperiplasmicspace.TeichoicacidsdonotoccurinGram-negativebacterialcellwalls..

現(xiàn)在是20頁(yè)\一共有91頁(yè)\編輯于星期三現(xiàn)在是21頁(yè)\一共有91頁(yè)\編輯于星期三OsidechainCorepolysaccharideLipidAChemicalStructureofLipopolysaccharide現(xiàn)在是22頁(yè)\一共有91頁(yè)\編輯于星期三MolecularModelofE.coliLipopolysaccharide現(xiàn)在是23頁(yè)\一共有91頁(yè)\編輯于星期三Thebondsbetweenthecarbohydratesinpseudopeptidoglycanareβ1-3insteadof'β1-4asinpeptidoglycan.

CellWallsofArchaebacteriaThearchaebacteriadonotcontainpeptidoglycanintheircellwallsasoccursineubacteria.N-acetylmuramicacidandD-aminoacidsarenotfoundinthecellwallsofarchaebacteria.(Differencesfromeubacteria)現(xiàn)在是24頁(yè)\一共有91頁(yè)\編輯于星期三Somearchaebacteriahavewallscomposedofpseudopeptidoglycan,whichresemblesthepeptidoglycanofeubacteriabutcontainsN-acetyltalosaminuronicacidinsteadofN-acetylmuramicacidandL.-aminoacidsinsteadoftheD-aminoacidsineubacterialcellwalls.現(xiàn)在是25頁(yè)\一共有91頁(yè)\編輯于星期三ProtoplastFormationPeptidoglycancanbedestroyedbycertainagentsforinstancelysozyme,thatbreaksthe1,4-glycosidicbondsbetweenN-acetylglucosamineandN-acetylmuramicacidinthemolecule.現(xiàn)在是26頁(yè)\一共有91頁(yè)\編輯于星期三Thedifferencebetweengram-positiveandgram-negativebacteriaisduetothephysicalnatureoftheircellwalls.Ifthecellwallisremovedfromgram-positivebacteria,theybecomegramnegative.

現(xiàn)在是27頁(yè)\一共有91頁(yè)\編輯于星期三Thepeptidoglycanseemstoactasapermeabilitybarrierpreventinglossofcrystalviolet.Gram-negativepeptidoglycanisverythin,notashighlycross-linked,andhaslargerpores.Alcoholtreatmentalsomayextractenoughlipidfromthegramnegativewalltofurtherincreaseitsporosity.Forthesereasons,alcoholmorereadilyremovesthepurplecrystalviolet-iodinecomplexfromgram-negativebacteria.TheMechanismofGramStaining現(xiàn)在是28頁(yè)\一共有91頁(yè)\編輯于星期三

ProceduresofGramStaining現(xiàn)在是29頁(yè)\一共有91頁(yè)\編輯于星期三GrampositiveorGramnegative?現(xiàn)在是30頁(yè)\一共有91頁(yè)\編輯于星期三現(xiàn)在是31頁(yè)\一共有91頁(yè)\編輯于星期三Structureofcytoplasmicmembrane2.3CytoplasmicMembraneFunctionofcytoplasmicmembraneMembrane現(xiàn)在是32頁(yè)\一共有91頁(yè)\編輯于星期三B.Colorizedelectronmicrographof'thecytoplasmicmembrane(CM)ofthebacteriumBacillussubtilis

revealsthecharacteristicrailroadtrackappearanceofthislipidbilayer.

StructureofCytoplasmicMembraneItisatypicalUNITMEMBRANE!A.Thetypicalcytoplasmicmembraneofprokaryoticandeukaryoticcellsisalipidbilayer,asillustratedhereshowingtheorientationsofthehydrophilic(tanspheres)andhydrophobic(black)endsofphospholipidsthatmakeupthisstructure.現(xiàn)在是33頁(yè)\一共有91頁(yè)\編輯于星期三Thecytoplasmicmembrane,ahighlyselectivebarrier,isconstructedprincipallyoflipid,withinwhichcertainproteinsareembedded.Membranescontainbothlipidsandproteins,althoughtheexactproportionsoflipidandproteinvarywidely.現(xiàn)在是34頁(yè)\一共有91頁(yè)\編輯于星期三Diagramofthestructureofcytoplasmicmembrane現(xiàn)在是35頁(yè)\一共有91頁(yè)\編輯于星期三3.Energyconservation-siteofgenerationanduseoftheprotonmotiveforce.

FunctionofMembrane1.Permeabilitybarrier-preventsleakageandfunctionasgatewayfortransportofnutrientsintoandoutofthecell.2.Proteinanchor-siteofmanyproteinsinvolvedintransport,bioenergetics,andchemotaxis.現(xiàn)在是36頁(yè)\一共有91頁(yè)\編輯于星期三

Rateofpermeability*

100

0.1

0.001

0.001

0.000001

0.0000001

0.00000001

Substance

Water

Glycerol

Tryptophan

Glucose

Chlorideion(Cl-)

Patassiumion(K+)

Sodiumion(Na+)

*Relativerate:Permeabilitywithrespecttopermeabilityofwatergivenas100

Comparativepermeabilityofmembranemoleculestovarious

現(xiàn)在是37頁(yè)\一共有91頁(yè)\編輯于星期三IntracellularMembraneSystemBacteriacellsdon’tcontainmembrane-enclosedorganelles.However,bacteriamayhavespecializedinvaginationsofthecytoplasmicmembrane.Theirfunctionmaybetoprovidealargermembranesurfaceforgreatermetabolicactivity.現(xiàn)在是38頁(yè)\一共有91頁(yè)\編輯于星期三StructureofMesosomeMesosomemaybeinvolvedinwallformationduringdivisionorplayaroleinchromosomereplicationanddistributiontodaughtercells.Itmayalsobeinvolvedinsecretoryprocesses現(xiàn)在是39頁(yè)\一共有91頁(yè)\編輯于星期三2.4CellularGeneticInformationNucleoid現(xiàn)在是40頁(yè)\一共有91頁(yè)\編輯于星期三BacterialChromosomeSupercoilingandchromosomestructureChromosomalcopynumber2.Plasmids現(xiàn)在是41頁(yè)\一共有91頁(yè)\編輯于星期三Micrographofabacteriumshowingthenucleoidregion(green)withinthecytoplasmwherethebacterialchromosomeoccurs現(xiàn)在是42頁(yè)\一共有91頁(yè)\編輯于星期三ThebacterialchromosomeisacircularDNAmacromoleculeexceptinStreptomyceswhereitislinearandRhodobacter

sphaffoides,whichhastwoseparatechromosomes.

BacterialChromosomeThebacterialchromosomeisusuallyasinglecovalentlyclosedcircularmolecule.ThetermnucleoidisusedtodescribeaggregatedDNAintheprokaryoticcell.現(xiàn)在是43頁(yè)\一共有91頁(yè)\編輯于星期三Rangeofgenomesizesinvirousgroupsoforganismsandtheorganellesofeukarya現(xiàn)在是44頁(yè)\一共有91頁(yè)\編輯于星期三Thebacterialchromosomeandsupercoiling:現(xiàn)在是45頁(yè)\一共有91頁(yè)\編輯于星期三ExampleofE.colicellThereareover50supercoileddomainintheE.colichromosome.ThetotalamountofDNAisabout4600kb.IfthetotalDNAisopenedandlinearized,itwouldbe1mminlength.Thethecellisonlyabout2-3umlong.SotopackagethismuchDNAintothecellrequiresthattheDNAbehighlysupercoiled.現(xiàn)在是46頁(yè)\一共有91頁(yè)\編輯于星期三ElectronmicrographofanisolatednucleoidreleasedfromE.coli.現(xiàn)在是47頁(yè)\一共有91頁(yè)\編輯于星期三Chromosomecopynumber

Bacteriathatreproduceasexuallyaretypicallyhaploidingeneticcomplement.Rapidlygrowingcellscontainmorethan1copyofthechromosome,andonlywhencellgrowthhasceaseddoesthechromosomenumberapproachonepercell.現(xiàn)在是48頁(yè)\一共有91頁(yè)\編輯于星期三

Reproductionofabacterialcellrequiresthereplicationofthebacterialchromosome.ThemicrographshowsthesequenceofsynthesisofnewcircularloopsofdoublehelicalDNA.Bacterianormallyreproducebybinaryfission.Theinwardgrowthoftheseptumdividestheparentcelltoproducetwoequal-sizedprogenycells.現(xiàn)在是49頁(yè)\一共有91頁(yè)\編輯于星期三Plasmidsdon’tcontainthegeneticinformationfortheessentialmetabolicactivitiesofthecell,buttheygenerallydocontaingeneticinformationforspecialfeatures.

PlasmidProkaryoticcellshavesmallextra-chromosomalgeneticelementscalledplasmids.現(xiàn)在是50頁(yè)\一共有91頁(yè)\編輯于星期三ResistantplasmidsColplasmidsConjugativeplasmidsMetabolicplasmids

MajorTypesofPlasmids現(xiàn)在是51頁(yè)\一共有91頁(yè)\編輯于星期三2.5CytoplasmicMatrixRibosomeandInclusionsRibosomeCarbonstoragepolymers–PHBandglycogenPhosphatepolymersSulfurGranulesGasVacuoles現(xiàn)在是52頁(yè)\一共有91頁(yè)\編輯于星期三Alleucaryoticandprocaryoticcellscontainribosomes,whichfunctionasthesitesofproteinsynthesis.RibosomesarecomposedoftwosubunitsProcaryoticribosomesarecalled70Sribosomes,andthoseofeucaryoticcellsareknownas80Sribosomes

RibosomesTheletterSreferstoSvedbergunits,whichindicatetherelativerateofsedimentationduringultra-high-speedcentrifugation現(xiàn)在是53頁(yè)\一共有91頁(yè)\編輯于星期三現(xiàn)在是54頁(yè)\一共有91頁(yè)\編輯于星期三Withinthecytoplasmofprocaryotic(andeucaryotic)cellsareseveralkindsofreservedeposits,knownasinclusions.Someinclusionsarecommontoawidevarietyofbacteria,whereasothersarelimitedtoasmallnumberofspeciesandthereforeserveasabasisforidentification.Amongthemoreprominentbacterialinclusionsarethefollowing:InclusionCarbonstoragepolymers–PHBandglycogenPhosphatepolymersSulfurGranulesGasVacuoles現(xiàn)在是55頁(yè)\一共有91頁(yè)\編輯于星期三Polyhydroxybutyricacid(PHB)PHBisalipidlikecompound-oneofthemostcommoninclusionbodiesinprokaryoticorganisms.PHBiscommonlyfoundasastoragematerialanduniquetobacteriaGlycogenisastarchlikepolymerofglucosesubunits.GlycogengranulesareusuallysmallerthanPHBgranules.AVibriospecies現(xiàn)在是56頁(yè)\一共有91頁(yè)\編輯于星期三Manymicroorganismsaccumulategranulesofpolyphosphate,whicharelargereservesofinorganicphosphatesthatcanbeusedinthesynthesisofATPPolyphosphategranule

inabacterialcellAPseudomonasspecies現(xiàn)在是57頁(yè)\一共有91頁(yè)\編輯于星期三ThesulfurglobulesinsidethecellsofpurplesulfurbacteriumChromatiumbuderiSomebacteria,includingmanyphotosyntheticbacteria,accumulateelementalsulfurgranulesasaresultoftheirmetabolism.現(xiàn)在是58頁(yè)\一共有91頁(yè)\編輯于星期三Gasvacuoles(blue)andstoragegranules(red)inthecyanobacteriumMicrocystisTheformationofgasvacuolesbyaquaticbacteriaprovidesamechanismforadjustingthebuoyancyofthecell.Manyaquaticcyanobacteriausetheirgasvacuolestomoveupanddowninthewatercolumn.現(xiàn)在是59頁(yè)\一共有91頁(yè)\編輯于星期三2.6ComponentsexternaltothecellwallFlagellaFimbriaeandpiliCapsulesandslimelayers現(xiàn)在是60頁(yè)\一共有91頁(yè)\編輯于星期三Motilityallowsthecelltoreachdifferentregionsofitsenvironment.Inthestruggleforsurvival,movementtoanewlocationmaymeanthedifferencebetweensurvivalanddeathofthecell.But,asinanyphysicalprocess,cellmovementiscloselytiedtoanenergyexpenditure,andthemovementofflagellaisnoexception.

Manyprokaryotesaremotile,andthisabilitytomoveindependentlyisusuallyduetoaspecialstructure,theflagellum(plural,flagella).現(xiàn)在是61頁(yè)\一共有91頁(yè)\編輯于星期三現(xiàn)在是62頁(yè)\一共有91頁(yè)\編輯于星期三Fourbasictypesofflagellararrangementsa.monotrichousb.amphitrichousc.lophotrichousd.peritrichous現(xiàn)在是63頁(yè)\一共有91頁(yè)\編輯于星期三Flagellaarearrangeddifferentlyondifferentbacteria.Inpolarflagellationtheflagellaareattachedatoneorbothendsofthecell.Occasionallyatuft(group)offlagellamayariseatoneendofthecell,anarrangementcalledlophotrichous.Inperitrichousflagellationtheflagellaareinsertedatmanyplacesaroundthecellsurface(perimeans"around").Thetypeofflagellation,polarorperitrichous,isoftenusedasacharacteristicintheclassificationofbacteria.現(xiàn)在是64頁(yè)\一共有91頁(yè)\編輯于星期三

TheflagellumofaGram-negativebacterium現(xiàn)在是65頁(yè)\一共有91頁(yè)\編輯于星期三Thefilamentofbacterialflagellaiscomposedofsubunitsofaproteincalledflagellin.

Thebaseoftheflagellumisdifferentinstructurefromthatofthefilament.Thereisawiderregionatthebaseoftheflagellumcalledthehook.Thehookconsistsofasingletypeofproteinandfunctionstoconnectthefilamenttothemotorportionoftheflagellum.

Thebasalbodyisanchoredinthecytoplasmicmembraneandcellwall.Thebasalbodyconsistsofasmallcentralrodthatpassesthroughasystemofrings.現(xiàn)在是66頁(yè)\一共有91頁(yè)\編輯于星期三Ingram-positiveBacteria,whichlacktheouterlipopolysaccharidelayer,onlytheinnerpairofringsispresent.SurroundingtheinnerringandanchoredinthecytoplasmicmembraneareapairofproteinscalledMot.Theseproteinsactuallydrivetheflagellarmotorcausingatorquethatrotatesthefilament.Afinalsetofproteins,calledtheFliproteinsfunctionasthemotorswitch,reversingrotationoftheflagellainresponsetointracellularsignals.Ingram-negativeBacteria,anouterringisanchoredinthelipopolysaccharidelayerandanotherinthepeptidoglycanlayerofthecellwall,andaninnerringislocatedwithinthecytoplasmicmembrane.現(xiàn)在是67頁(yè)\一共有91頁(yè)\編輯于星期三Themovementofaprocaryoticflagellumresultsfromrotationofitsbasalbodyandissimilartothemovementoftheshaftofanelectricmotor.Bacterialcellscanalterthespeedanddirectionofrotationofflagellaandthusarecapableofvariouspatternsofmotility.現(xiàn)在是68頁(yè)\一共有91頁(yè)\編輯于星期三Fimbriaecanbeevenlydistributedovertheentiresurfaceofthecell.Theycannumberanywherefromafewtoseveralhundredpercell.Fimbriaeallowacelltoadheretosurfacesincludingthesurfacesofothercells.

Piliareusuallylongerthanfimbriaeandnumberonlyoneortwopercell.PilifunctiontojoinbacterialcellspriortothetransferofDNAfromonecelltoanother.Fpilus現(xiàn)在是69頁(yè)\一共有91頁(yè)\編輯于星期三Manyprokaryotescontainacellsurfacelayercomposedofatwo-dimensionalarrayofprotein.TheselayersarecalledS-layers.S-layershavebeendetectedinrepresentativesofvirtuallyeveryphylogeneticgroupingofBacteriaandarenearlyuniversalamongArchaea.InsomespeciesofArchaeatheS-layerisalsothecellwall.ParacrystallineSurfaceLayers(S-Layers)現(xiàn)在是70頁(yè)\一共有91頁(yè)\編輯于星期三ThemajorfunctionofS-layersisunknown.Astheinterfacebetweenthecellanditsenvironment,itislikelythatincellsthatproducethemtheS-layeratleastfunctionsasanexternalpermeabilitybarrier,allowingthepassageoflow-molecular-weightsubstanceswhileexcludinglargemolecules.現(xiàn)在是71頁(yè)\一共有91頁(yè)\編輯于星期三2.7BacterialEndosporesCertainspeciesofbacteriaproducespecialstructurecalledendospores.Theyareveryresistanttoheatandcannotbedestroyedeasily,evenbyharshchemicals.Endosporesarealsoresistanttootherharmfulagentssuchasdrying,UVradiation,acidsandchemicaldisinfectants.現(xiàn)在是72頁(yè)\一共有91頁(yè)\編輯于星期三SporulatingcellCentralcoreCortexSporecoat/membraneexosporiumMicrographofaendosporeVegetativecell現(xiàn)在是73頁(yè)\一共有91頁(yè)\編輯于星期三現(xiàn)在是74頁(yè)\一共有91頁(yè)\編輯于星期三Manyprokaryoticorganismssecreteontheirsurfacesslimyorgummymaterials.Avarietyofthesestructuresconsistofpolysaccharide,andafewconsistofprotein.Thetermscapsuleandslimelayerarefrequentlyusedtodescribepolysaccharidelayers.Demonstrationofthepresenceofacapsuleisusuallybymeansofnegativestaining

CapsulesandSlimeLayers現(xiàn)在是75頁(yè)\一共有91頁(yè)\編輯于星期三LowpHvalue,andcontainssmallacid-solublesporeproteins(SASPs)StructureofDPA

PropertiesofEndosporeandItsResistanceContainingabundantDPA(dipicolinicacid)whichiscombinedwithcalciumions.Lowerwatercontent–only10-30%ofthewatercontentofthevegetativecell.現(xiàn)在是76頁(yè)\一共有91頁(yè)\編輯于星期三Sporulationinvolvesaverycomplexseriesofeventsincellulardifferentiation.Bacterialsporulationdoesnotoccurwhencellsaredividingexponentiallybutonlywhengrowthceasesowingtotheexhaustionofanessentialnutrient.Thus,cellsofBacillusceasevegetativegrowthandbeginsporulationwhenakeynutrientsuchasthecarbonornitrogensourcebecomeslimiting.EndosporeFormatiom現(xiàn)在是77頁(yè)\一共有91頁(yè)\編輯于星期三

Stagesinendosporeformation1.Axialfilamentformation2.Septumformatiom3.Engulfmentofforespore4.Cortexformation5.Coatsynthesis6.Completionofcoatsynthesis,Increaseinrefractilityandheatresistance7.Lysisofsporangium,sporeliberation現(xiàn)在是78頁(yè)\一共有91頁(yè)\編輯于星期三現(xiàn)在是79頁(yè)\一共有91頁(yè)\編輯于星期三1.Activation–Usuallyresultsfromtreatmentslikeheating.2.Germination–

Breaksspore’sdormantstate.Thisprocessischaracterizedbysporeswelling,lossofresistancetoheatandotherstresses,lossofrefractilityandincreaseinmetabolicactivity.3.Outgrowth–

Thesporeprotoplastmakesnewcomponentsanddevelopsoncemoreintoanactivebacterium.SporeGermination現(xiàn)在是80頁(yè)\一共有91頁(yè)\編輯于星期三SeveralBacillusspecies,mostnotablyB.popilliaeandB.thuringiensis,produceintracellularcrystalsoftoxicglycoproteinswhentheysporulate.ToxiccrystalsParasporalCrystal(Spore-companionedcrystal)現(xiàn)在是81頁(yè)\一共有91頁(yè)\編輯于星期三2.8ComparisonofTheProkaryoticandEucaryoticCellPropertiesProkaryoteEukaryotePhylogeneticgroupsBacteria,ArchaeaEukarya:Algae,fungi,protozoa,plants,animalsSizeGenerallysmall,usually<2μmindiameterUsuallylarge,2to100μmindiameterNuclearmembranesAbsentPresentNucleolusAbsentPresentDNANotmitosisMitosis;mitoticapparatuswithmicrotubularspindle現(xiàn)在是82頁(yè)\一共有91頁(yè)\編輯于星期三PropertiesProkaryoteEukaryoteCytoplasmicmembraneUsuallylackssterols;hopanoidsmaybepresentSterolsusuallypresent;hopanoidsabsentRibosomes70sinsize80s,exceptforribosomesofmitochondriaandchloroplastswhichare70sMembranousorganellesAbsentSeveralpresentRespirationsystemPartofcytoplasmicmembrane;mitochondriaabsentInmitochondria;hydrogenosomesincertainanaerobicspeciesCellwallsPresent(inmost),composedofpeptidoglycan(bacteria),protein,otherpolysaccharides,glycoprotein(Archaea)Presentinplants,algae,fungi,usuallypolysaccharide;absentinanimals,mostprotozoa現(xiàn)在是83頁(yè)\一共有91頁(yè)\編輯于星期三TheirDNAisassociatedwithhistoneproteins.membrane-boundedorganelles9+2typeflagellaEucaryoticCell現(xiàn)在是84頁(yè)\一共有91頁(yè)\編輯于星期三Thechiefdistinguishingcharacteristicsofprocaryoticcellsare:1.Theirgeneticmaterial(DNA)isnotenclosedwithinamembrane.2.Theylackothermembrane-boundedorganelles.3.TheirDNAisnotassociatedwithhistoneproteins.4.Theircellwallsalmostalwayscontainthecomplexpolysaccharidepeptidoglycan.5. Theyusuallydividebybinaryfission.Duringthisprocess,theDNAiscopiedandthecellsplitsintotwocells.

現(xiàn)在是85頁(yè)\一共有91頁(yè)\編輯于星期三Summary1.Prokaryoticgeneticmaterialis