《微生物学》双语教学授课教案

《微生物学》双语教学

授课教案

1.iculardisease.Koch9spostulates：

Koch'spostulatesareanumberofcriteriathathavebeenusedinthepasttoprovethata

bacteriumisresponsibleforaparticulardisease.

1.Thebacteriashouldbefoundinallcasesandatallsitesofthedisease.

2.Thebacteriashouldbeisolatedfromtheinfectedpersonandmaintainedinpureculture.

3.Thepureculturedmicrobeshouldcausesymptomsofthediseaseoninoculationintoa

susceptibleindividual.

4.Thebacteriashouldbereisolatedfromtheintentionallyinfectedhost.

Theimportanceofmicrobiology：

microbesinourbody

1.EveryonehasmicroorganismsinandonthebodySomemicroorganismsliveinhumansand

otheranimalsandareneededtomaintaintheanimalshealth,thesemakeupthenormalflora

(正常菌群)；

2.SomeMicroorganismscausedisease.

3.Thedisease-producingpropertiesofaspeciesofmicrobeandthehost'sresistanceare

importantfactorsindeterminingwhetherapersonwillcontractadisease.

2.MicrobesandHumanWelfare

1.Microorganismsdegradedeadplantsandanimalsandrecyclechemicalelementstobe

usedbylivingplantsandanimals.

2.Bacteriaareusedtodecomposeorganicmatterinsewage.Bioremediationprocessesuse

bacteriatocleanuptoxicwastes.

3.Bacteriathatcausediseasesininsectsarebeingusedasbiologicalcontrolsofinsectpests.

Biologicalcontrolsarespecificforthepestanddonotharmtheenvironment.

4.UsingrecombinantDNA,bacteriacanproduceimportanthumanproteins,suchasinsulin,

beta-endorphin,andhepatitisBvaccine.Microorganismscanbeusedtohelpproduce

foods.Theyarealsofoodsources(single-cellprotein)themselves.

3.Asabasicbiologicalscience：microorganismsarethebestmodelsystemsforunderstanding

basiclifeprocesses.

衿AHcellshavemuchincommon,whatistrueforE.collisalsotrueforelephant,onlymore

so

衿Simpleyetrepresentative

田Easinessandquicknesstogrowlargequantity

Commoncharacterizesofmicroorganism,Bigsurface/volume

•Highabsorptionandtransformation

•Rapidgrowthandreproduction

•Easinesstovariation

•highadaptationtoenvironment

•Diversity

Reviewquestion

1.Matchthefollowingpeopletotheircontributiontowardtheadvancementofmicrobiology.

—Ehrlich(a)Firsttoobservebacteria

—Fleming(b)Firsttoobservecellsin

—Hookeplantmaterialandname

_Kochthem

_Lister(c)Disprovedspontaneous

_Pasteurgeneration

_VanLeeuwenhoek(d)Provedthatmicroorganismscancausedisease

(e)Discoveredpenicillin

(f)UsedthefirstsyntheticchemotheraputicagentFirsttoemploy

disinfectantsinsurgicalprocedures

2.Matchthefollowingmicroorganismstotheirdescriptions.

_Algae(a)Notcomposedofcells

—Bacteria(b)Cellwallmadeofchitin

—Fungi(c)Cellwallmadeof

—Protozoompeptidoglycan

_Viruses(d)Cellwallmadeofcellulose;photosynthetic

(e)Complexcellstructurelackingacellwall

3.Brieflystatetheroleplayedbymicroorganismsineachofthefollowing.

(a)Biologicalcontrolofpests

(b)Recyclingofelements

(c)Normalflora

(d)Sewagetreatment

(e)Humaninsulinproduction

4Themicrobeswerefirstformallyobservedinthemid-1600*8,butthecelltheorywasn't

enunciateduntil1839.Writeabriefessayexplainingwhymicrobiologydidnotbecomea

formallyrecognizedscienceuntilPasteur'stime.

5.CompareandcontrasttheworksofLouisPasteurandRobertKoch,intermsofbothappliedand

basicscience.

6.Microorganismscanbebothbeneficialandharmfultohumans.Althoughwetendtoemphasize

theharmfulmicroorganisms(infectiousdiseaseagents),manymorearebeneficialthanharmful.

•Inwhatwaysaremicroorganismsimportantinthefood,agriculture,andindustries?

7.LouisPasteurzsworkonspontaneousgenerationledtothedevelopmentofmethodsforcontrol

ofthegrowthofmicroorganisms.RobertKochdevelopedcriteriaforthestudyofinfectious

microorganisms,anddevelopedthefirstmethodsforthegrowthofpureculturesof

microorganisms.BeijerinckandWinogradskystudiedbacteriainsoilandwater,anddevelopedthe

enrichmentculturetechnique.Inthetwentiethcentury,basicandappliedmicrobiologyhave

workedhandinhandtoyieldanumberofimportantpracticaladvancesandarevolutionin

molecularbiology.

•HowdidPasteurAsfamousexperimentdefeatthetheoryofspontaneousgeneration?

•HowcanKoch'spostulatesprovecauseandeffectinadisease?

•Whowasthefirstpersontousesolidculturemediainmicrobiology?

•Whatadvantagesdosolidmediaofferforthecultureofmicroorganisms?

•Whatistheenrichmentculturetechniqueandwhywasitausefulnewmethodin

microbiology?

Chapter2prokayoticmicroorganism（原核微生物）第二章

原核微生物

prokaryoticcells

Thechiefdistinguishingcharacteristicsofprocaryoticcellsare:

1.geneticmaterial（DNA）isnotenclosedwithinamembrane.

2.Theylackothermembraneboundedorganelles.

3.TheirDNAisnotassociatedwithhistoneproteins（specialchromosomal

proteinsfoundineucaryotes）.Theircellwallsalmostalwayscontainthe

complexpolysaccharidepeptidoglycan（肽聚糖）.Bacteria（细菌）and

archaeobacteria（古细菌）

Bacteriaaresmall,single-celled,microorganismsthatbelongtoagroupcalledprokaryotes.

Bacteriaareubiquitous.Theyareahighlysuccessfulanddiversegroupoforganismsthatcan

obtainenergyandcarbonfromawiderangeofsourcesandthereforecancolonizeeverynicheon

ourplanetfromdeepoceantrenchestovolcaniccraters.Inthe1970s,usingDNAsequencing

information,itwasfoundthatthegroupweknowasthebacteriacouldbesplitintotwo,the

eubacteriaandthearchaeobacteriaanditappearsthatthesetwogroupsevolvedaway

fromeachotherveryearlyinthehistoryoflivingthingsataboutthesametimethatthe

firstgroupofeukaryoticcellsevolved.Membersoftheeubacteriaincludesomeofthemore

familiarbacteriasuchasEscherichiacolt（大肠埃希氏菌）andStaphylococcusaureus（金

黄色葡萄球菌）andaretheprokaryotesthatarebeststudiedandunderstood.The

archaebacteriaareaverydiversegroupoforganisms,whichdifferfromtheeubacteria（真细

菌0inanumberoffeatureshaving,inparticular,verydifferentcellwallsandmembranes.

Thisgroupincludesbacteriathatarecapableofexistinginextremeenvironments。

Size,Shape,andArrangementofBacterialCells

1Mostbacteriaarefrom0.20to2.0/Nmindiameterandfrom2to8Mminlength.

2Thethreebasicbacterialshapesarecoccus（spheres）,bacillus（rods）,andspiral（twisted）.

3Inadditiontothethreebasicshapes,therearestar-shapedcells（genusStella）and

recentlydiscoveredsquare,flatcells（halophilic（嗜盐的）archaeobacteria）and

triangularcells（Haloarcula）

4theshapeofabacteriumisdeterminedbyheredity.However,anumberof

environmentalconditionscanalterthatshape.Pleomorphic（多型性的）bacteriacan

assumeseveralshapes.

GramStain：

Theeubacteriaarefrequentlydividedintotwogroupsonthebasisoftheirreactiontoastain

devisedbyChristianCramin1884.Thedifferentialreactiontothestainingprocedureis

becauseofthestructureofthecellwallinthesetwogroupsofbacteria.Gram-positivebacteria

haveasinglemembranecalledthecytoplasmic（orplasma）membrane,surroundedbyathick

layerofpeptidoglycan（20-80nm）.TheGram-negativebacteriahaveonlyathinlayerof

peptidoglycan（1-3nm）butontheoutsideofthisthereisafurtheroutermembranewhichacts

asanadditionalbarrier.

TheprocedurefortheGramstainisasfollows.Fixedcellsarestainedwithadarkstainsuch

ascrystalviolet,followedbyiodinewhichcomplexeswiththestaininthecellwallofthe

bacteria.Alcoholisadded,whichwashesthedarkstainofcrystalviolet-iodineoutofceilsthat

havethincellwallsbutnotfromthosethathavethickcellwalls.Finally,apalerstainsuchas

carbolfuschin,calledacounterstain,isaddedwhichstainsthedecolorizedcellspinkbutisnot

seenonthedarkstainingcellsthatretainedthefirststain.Thecellsthatretainthestain（with

thickcellwalls）arecalledGram-positiveandappeardarkpurpleunderlightmicroscopy.The

onesthatlosethestain（withthincellwallsandanoutermembrane）arecalledGram-negative

andstainpinkorpalepurple

TheCellWall

1.Thecellwallsurroundstheplasmamembraneandprotectsthecellfromchangesin

osmoticpressure（渗透压）andprovidesrigidityandstrength.

2.Thebacterialcellwallconsistsofpeptidoglycan（肽聚糖）,apolymerconsistingofNAG

andNAMandshortchainsofaminoacids.

3.Gram-positive（革兰氏阳性）cellwallsconsistofmanylayersofpeptidoglycanandalso

containteichoicacids（垣酸）.

4.Gram-negative（革兰氏阴性）bacteriahavea

lipidprotein-lipopolysaccharide-phospholipidoutermembranesurroundingathin

peptidoglycanlayer.

5.Theoutermembraneprotectsthecellfromphagocytosisandpenicillin（青霉素）,lysozyme

（溶菌酶），andotherchemicals.

6.Porins（孑L蛋白）areproteinsthatpermitsmallmoleculestopassthroughtheouter

membrane;specificchannelproteinsallowothermoleculestomovethroughtheouter

membrane.

7.Thelipopolysaccharide（脂多糖，LPS）componentoftheoutermembraneconsistsof

sugarsthatfunctionasantigensandlipidA,whichisanendotoxin（内毒素）.

teichoicacid:

Gram-positivecellwallsalsocontainlargeamountsofanotherpolymer,calledteichoicacid,

madeupofglycerolorribitoljoinedbyphosphategroups.D-Ala,glucoseorsugarsmaybe

attachedtotheglycerolorribitolandthepolymersareattachedeitherdirectlytotheNAMin

thepeptidoglycanortolipidsinthemembrane（inthiscasetheyarecalledlipoteichoicacids）.

Thefunctionofthesemoleculesisunclearbuttheymayhavearoleinmaintainingthestructure

ofthecellwallandinthecontrolofautolysis.

periplasmicspace（周质空间）

TheoutermembraneofGram-negativebacteriaactsasanadditionalbarrierprotectingthe

peptidoglycanfromtoxiccompoundssuchaslysozymewhichactonthecellwall.It

createsanaqueousspacebetweenthetwomembranescalledtheperiplasmicspacewhich

isthoughttohaveagel-likestructurewithaloosenetworkofpeptidoglycanrunning

throughit.Estimatesastothewidthofthepeptidoglycanvaryfrom1-71nmbutithas

provedtobedifficulttoobtainarealdefinitivevalue.Theperiplasmicspacecontainsa

rangeofproteinsassociatedwith:

•transportofnutrientsintothecell;

•enzymesthatareinvolvedinnutrientacquisitionsuchasproteases;

•enzymesthatdefendthecellagainsttoxicchemicalssuchasB-lactamasesthatdestroy

penicillin.

outermembrane

TheoutermembraneofGram-negativebacteriaismadeupofphospholipids

membrane,butitalsocontainssomeuniquefeatures

1.PoresformedbyproteinscalledporinssuchasOmpFandOmpCthatallowthepassive

diffusionofsmallmoleculesintotheperiplasmicspace.

2.AnabundantsmalllipoproteincalledBraun'slipoproteinthatiscovalentlyboundto

thepeptidoglycanandisembeddedintheoutermembranebyitshydrophobiclipid,

thereforeholdingthepeptidoglycanandoutermembraneclosetogether.

3.LPSmoleculesarefoundintheouterleafletoftheoutermembraneprojectingintothe

surroundingmedium.

Atypical（缺陷的）cellwalls

1.Mycoplasma（支原体）isabacterialgenusthatnaturallylackscellwalls.

2.Archaeobacteriahavepseudomurein（假肽聚糖）；theylackpeptidoglycan.

3..Lformsaremutantbacteriawithdefectivecellwalls.

Archaeobacterialcellwalls

Oneofthedistinctivefeaturesofarchaebacteriaisthenatureofthelipidsintheplasma

membranewhich,unliketheester-linkedlipidsofeubacteriaandeukaryotesareether-linkedto

glycerol.Theyarealsolongchainedandbranched.Archaebacterialcellwallsandenvelopes

showgreatdiversityandcomplexityinstructure.Theydonotcontainpeptidoglycanalthough

somedohaveasimilarcompoundcalledpseudomureinwhichcontainsN-acetyl-alosaminuronic

acidinplaceofmuramicacid.AnothercommontypeofcellwallistheS-layer,a

two-dimensional,paracrystalline,arrayofproteinorglycoproteinonthecellsurface.Others

havethickpolysaccharidewallsoutsidetheirplasmamembrane.

DAMAGETOTHECELLWALL

peptidoglycanusedtobeatargetforantimicrobialagentsthatdestroyprokaryoticcells

specifically,butdonotharmeukaryoticcells;anexampleofthisistheantibioticpenicillin

(TopicF7).Lysozyme,anaturalantibacterialagentfoundintearsandnaturalsecretions,breaks

downthelinkagebetweenNAMandNAG.Removalofthecellwallunderconditionswherethe

osmolarityofthemediumisthesameastheinsideofthecell(isotonicsolution)resultsinthe

formationofroundprotoplasts(原生质体)(Gram-positives)orspheroplasts(球形体)

(Gram-negatives)whichsurviveaslongastheisotonicityismaintained.Thesestructureslyse,

however,ifplacedinadilutemedium,illustratingtheimportanceofpeptidoglycantothecells*

survival.

1.Inthepresenceoflysozyme,gram-positivecellwallsaredestroyedandtheremaining

cellularcontentsarereferredtoasaprotoplast.

2.Inthepresenceoflysozyme,gram-negativecellwallsarenotcompletelydestroyedand

theremainingcellularcontentsarereferredtoasaspheroplast.

3.Protoplastsandspheroplastsaresubjecttoosmoticlysis.

4.Antibioticssuchaspenicillininterferewithcellwallsynthesis.

PLASMA(CYTOPLASMIC)MEMBRANE

1Theplasmamembraneenclosesthecytoplasmandisaphospholipidbilayerwith

protein(fluidmosaic).

2mostofbacterialackofsteriol(固醇)

3Theplasmamembraneisselectivelypermeable.

4Plasmamembranescarryenzymesformetabolicreactions,suchasnutrient

breakdown,energyproduction,andphotosynthesis.

5Mesosomes—irregularinfoldingsoftheplasmamembrane—arenowconsidered

artifacts

6.Plasmamembranescanbedestroyedbyalcoholsandpolymyxin.

CYTOPLASM

1Cytoplasmisthefluidcomponentinsidetheplasmamembrane.

2Thecytoplasmismostlywater,withinorganicandorganicmolecules,DNA,

ribosomes,andinclusions.

RIBOSOMES

1Thecytoplasmofaprocaryotecontainsnumerous70Sribosomes;ribosomesconsistof

rRNAandprotein.

2Proteinsynthesisoccursatribosomes;thiscanbeinhibitedbycertainantibiotics.

INCLUSIONS

1Inclusions（内含物）arereservedepositsfoundinprocaryoticandeucaryoticcells.

2Amongtheinclusionsfoundinbacteriaaremetachromaticgranules（异染粒）

（inorganicphosphate）,polysaccharidegranules（,多糖，usuallyglycogenorstarch）,lipid

inclusions（脂滴）,sulfurgranules（硫粒），carboxysomes（,竣酶体，ribulose1,5-diphosphate

carboxylase）,andgasvacuoles（气泡）.

NUCLEARAREA

1.ThenuclearareacontainstheDNAofthebacterialchromosome.Bacteriacanalsocontain

plasmids,whichareextrachromosomalDNAcircles.

capsuleorslimelayer

1.capsule（荚膜）orslime（黏液层）layerisagelatinouspolysaccharideand/or

polypeptidecovering.

2.Capsulesmayprotectpathogensfromphagocytosis（吞噬）.

3.Capsulesprovideadherencetosurfaces,preventdesiccation,andmayprovide

nutrients.

FLAGELLA

1.Flagella（鞭毛）arerelativelylongfilamentousappendagesconsistingofafilament,hook,

andbasalbody.

2.Procaryoticflagellarotatetopushthecell.Motile（运动）.

3.bacteriaexhibittaxis（趋性）一positivetaxisismovementtowardanattractantand

negativetaxisismovementawayfromarepellent.

FIMBRIAEANDPILIF

1.fimbriae（菌毛）andpili（性毛）areshort,thinappendages.

2.Fimbriaehelpcellsadheretosurfaces.

3.PilijoincellsforthetransferofDNAfromonecelltoanother.

ENDOSPORES（芽狗）

1.Endosporesarerestingstructuresformedbysomebacteriaforsurvivalduringadverse

environmentalconditions.

2.Theprocessofendosporeformationiscalledsporulation;thereturnofanendosporetoits

vegetativestateiscalledgermination.

Endosporesareamethodassurvival,notoneofreproduction.Certainbacteriawillformaspore

withintheircellmembrane（anendospore）thatallowsthemtowaitoutdeteriorating

environmentalconditions.Certaindiseasecausingbacteria（suchastheonethatcausesthedisease

Anthrax）canbevirulent（capableofcausinganinfection）1300yearsafterformingtheir

endospore!）

BACTERIALDIVISION

1.Thenormalreproductivemethodofbacteriaisbinaryfission,inwhichasinglecell

dividesintotwoidenticalcells.

2.Somebacteriareproducebybudding.,aerialsporeformation,orfragmentation.

binaryfission（二分裂）

Themethodbywhichbacteriareproduce.ThecircularDNAmoleculeisreplicated;

thenthecellsplitsintotwoidenticalcells,eachcontaininganexactcopyofthe

originalcelTsDNA.

Actinomyces

Actinomycetes（放线菌）arefilamentous,gram-positivebacillithatformabranching

mycelium.

Cyanobacteria（蓝细菌）：

Blue-greenbacteria;unicellularorfilamentouschainsofcellsthatcarryout

photosynthesis.

Rickttsias,chlamydiasandmycoplasmas

Therickttsias（立克次氏体）andchlamydias（衣原体）aregram-negativeobligateintracellularparasites

由alkeymetabolicenzymes.

Therickettsiasareextremelysmall,pleomoiphicrodsorcoccobacillithatcannotsynthessiztheirownATR

Mosthaveacomplexlife-stylethatcycesbetweenarthropodvectorsandvertebratehosts.

Therickettsiasareususllytransmittedbytickortickfeces.

Thechlamydiasaresmall,gram-negative,pleomorphic,intracellularparasitesthathaveno

catabolicpathways.Theyexistintwoforms:theelementarybody,whichistheformtransmitted

betweenhumanhoststhroughdirectcontactandbodysecretions,andthereticulatebody,which

multipliesintracellularly.

Chlamydia（沙眼衣原体）istheagentofseveralSTDs:NGU（nongonococcal

urethritis）,pelvicinflammatorydisease,andlymphogranulomavenereum.Italsocausesocular

trachoma,aseriouseyeinfection.

Chlamydia〃〃6〃切0〃〃屋（肺炎衣原体）istheagentofrespiratoryinfectionsinyoungadultsand

asthmatics.

Chlamydiapsittaci(鹦鹉热衣原体)istheagentofornithosis,aninlluenza-likediseasecarriedby

birdsthathasserioussystemiccomplicationsifuntreated.Antibiotictherapyisusuallysuccessful.

Mycoplasmas(支原体)aretinypleomorphicbacteriathatlackacellwall.Althoughmost

speciesareparasitic,mycoplasmascanbeculturedoncomplexartificialmedia.Theyare

consideredmembraneparasitesbecausetheybindtightlytoepithelialliningsoftherespiratory

andurogenitaltracts.

Mycoplasma。应c/e(肺炎支原体)istheagentofprimaryatypicalpneumonia(walking

pneumonia).

M.比汉人型支原体)andM.(胭支原体)areagentsofsexuallytransmitted

infectionsofthereproductivetractandkidneys,andmorerecently,offetalinfections.

M.incognitosisarecentlyidentifiedpathogenthatcausessystemicinfectionby

suppressingtheimmunesystem.

Chapter2Reviewquestion

1.Diagrameachofthefollowingflagellararrangements:

(a)Lophotrichous

(b)Monotrichous

(c)Peritrichous

2.EndosporeformationiscalledItisinitiated

by—.Formationofanewcellfromanendosporeiscalled_L.Thisprocessistriggeredby_

3.Drawthebacterialshapeslistedina,b,andc.Showhowd,e,andfarespecialconditions

ofa,b,andc,respectively.

(a)Spiral(d)Spirochete

(b)Bacillus(e)Streptobacilli

(c)Coccus(f)Staphylococci

4.Listthreedifferencesbetweenprocaryoticandeucaryoticcells.

5.Matchthestructurestotheirfunctions.

CellwallAProtectionfromosmoticlysis

Endospore--------B:Attachment

FimbriaeC:Protectionfromphagocytes

FlagellaD:Resting

caupsleE:Proteinsynthesis

PlasmamembraneF:Selectivelypermeable

RibosomeI：Transferofgeneticmaterial

6.Ofwhatvalueiseachofthefollowingtothecell?

(a)Metachromaticgranules

(b)Polysaccharidegranules

(c)Lipidinclusions

(d)Sulfurgranules

(e)Carboxysomes

(f)Gasvacuoles

7.Whyisanendosporecalledarestingstructure?Ofwhatadvantageisanendosporetoa

bacterialcell?

8.Compareandcontrastthefollowing:

Protoplastsandspheroplastspenicillinandlyzosome

Flagellaandfimbriaerickttsiaeandchlamydias

9.Answerthefollowingquestionsusingthediagramsbelow,whichrepresentcrosssections

ofbacteria]cellwalls.

(a)Whichdiagramrepresentsagram-positivebacterium?Howcanyoutell?

(b)ExplainhowtheGramstainworkstodistinguishbetweenthesetwotypesofcell

walls.

(c)Whydoespenicillinhavenoeffectonmostgramnegativecells?

(d)Howdoessentialmoleculesentercellsthrougheachwall?

Teichoicacid

Peptidoglycan

Cellmembrane

10.Whycanprocaryoticcellsbesmallerthaneucaryoticcellsandstillcarryonallthe

functionsforlife?

11.Twotypesofprocaryoticcellshavebeendistinguished:eubacterialandarchaeobacterial.How

dothesecellsdifferfromeachother?Howaretheysimilar?

12.WhatistheevolutionaryadvantageofthemonolayeroftenfoundinArchaealmembranes?

13.Bacillussubtilisisacommonsoilbacterium.WhatgenusdoesB.subtilisbelongto?

14.Althoughprokaryotesandeukaryotesaredistinguishedbynuclearstructure,otherimportant

differencesexistbetweenthesetwocelltypes.Prokaryotesaresmallerinsizethaneukaryotes,and

eukaryotescontainamembrane-enclosednucleusandorganelleswithinwhichmanyimportant

functionsarecarriedout.Thesmallsizeofprokaryoticcellsaffectstheirphysiology,growthrate,

andecology.

•Listthreemorphologicaltypesofprokaryotes.

•Whatisaflagellum,andwhatdoesitdo?

•Whatphysicalpropertyofcellsincreasesascellsbecomesmaller?

15.ThecellwallsofBacteriacontainapolysaccharidecalledpeptidoglycan.Thismaterial

consistsofstrandsofalternatingrepeatsofN-acetylglucosamineandN-acetylmuramicacid,with

thelattercross-linkedbetweenstrandsbyshortpeptides.Archaealackpeptidoglycanbutcontain

wallsmadeofotherpolysaccharidesorofprotein.Theenzymelysozymedestroyspeptidoglycan,

leadingtoceillysis.

•Listthemonomericcomponentsofpeptidoglycan.

•Whyispeptidoglycansuchastrongmacromolecule?

•Howdoespsuedopeptidoglycanresemblepeptidoglycan?Howdothetwomoleculesdiffer?

•Howisaprotoplastgenerated?

16.1nadditiontopeptidoglycan,Gram-negativeBacteriacontainanoutermembraneconsistingof

lipopolysacchaaride,aprotein,andlipoprotein.Proteinscalledporinsallowforpermeability

acrosstheoutermembrane,andaspacecalledtheperiplasmispresent,whichcontainsvarious

proteinsinvolvedinimportantcellularfunctions.

•WhatcomponentsconstitutetheLPSlayerofGram-negativeBacteria?

•Whatisthefunctionofporins,andwherearetheylocatedinaGram-negativecellwall?

•WhydoesalcoholreadilydecolorizeGram-negativebacteria?

17.Theendosporeisahighlyresistantdifferentiatedbacterialcellproducedbycertaintypesof

Gram-positiveBacteria.Sporeformationleadstoanearlydehydratedsporecorethatcontains

essentialmacromoleculesandavarietyofsubstances,suchascalciumdipicolinateandsmall

acid-solubleproteins,absentfromvegetativecells.Sporescanremaindormantindefinitelybut

germinatequicklywhentheappropriatetriggerisapplied.

•Whatisdipicolinicacid,andwhereisitfound?

•WhatareSASPs,andwhataretheirfunctions?

•Whathappenswhenanendosporegenninates?

chapter3eukaryoticmicroorganisms

第3章真核微生物

Eukaryotecell

Atypeofcellfoundinmanyorganismsincludingsingle-celledprotozoomandmulticellularfungi,

plants,andanimals;characterizedbyamembrane-boundednucleusandothermembraneous

organelles

eukaryoticcellsconstruct

Appendages（cilia,flagella）,glycocalyx,cellwall,cytoplasmic（orcell）membrane,ribosomes,

organelles（nucleus,nucleolus,endoplasmicreticulum,Golgiapparatus,mitochondria,chloroplasts,

cytoskeleton,microfilaments.

Maincharactersticofeukaryticcells

1.Thenucleus,whichcontainsDNAintheformofchromosomes,isthemostcharacteristic

eukaryoticorganelle.

2.Thenuclearmembraneisconnectedtoasystemofparallelmembranesinthecytoplasm,

calledtheendoplasmicreticulum.

3.Theendoplasmicreticulumprovidesasurfaceforchemicalreactions,servesasa

transportingnetwork,andstoressynthesizedmolecules.

4.805ribosomesarefoundinthecytoplasmorattachedtotheendoplasmicreticulum.

5.TheGolgicomplexconsistsofcisternae.Itfunctionsinsecretion,carbohydratesynthesis,

andglycoproteinformation.

6.MitochondriaaretheprimarysitesofATPproduction.Theycontainsmall70Sribosomes

andDNA,andtheymultiplybyfission.

7.Chloroplastscontainchlorophyllandenzymesforphotosynthesis.Likemitochondria,they

contain70SribosomesandDNAandmultiplybyfission.

8.LysosomesareformedfromGolgicomplexes.Th