微生物英文名词解释

1.Mycoplasma：Themycoplasmaareagroupofthesmallestorganismswithoutcellwallthatcanbefree-livinginnature,canpassthroughbacterialfilterandalsogrowonlaboratorymedia.2.Chlamydia：ChlamydiaaresmallGram-negativebacteriawhichareobligateintercellularparasiteslikevirus,butdifferfromtheminthattheyhavebothRNAandDNA,ribosome,cellwall,anddividedbybinaryfission.3.Lformsofbacteria：Inosmoticallyprotectivemedia,removalofthebacterialwallwithlysozymeorpenicillinliberateprotoplastsfromGram-positivecellsandspheroplastsfromGram-negativecells.Ifsuchwall-defectivecellsareabletogrowanddivide,theyarecalledLforms.Lformsaredifficulttocultivate.Theyrequireaspecialmedia.SomeLformcanreverttothenormalbacillaryform.Lforminthehostmayproducechronicinfectionthatarerelativelyresistanttoantibiotictreatment.4.Capsule：Manybacteriasynthesizelargeamountsofextracellularpolymerwhengrowingintheirnaturalenvironments.Whenthepolymerformsacondensed,well-definedlayercloselysurroundingthecell,itiscalledthecapsule.Withoneknownexception(thepolypeptidecapsule),thepolymerispolysaccharide.5.Pyrogen：Thisisafever-producingsubstancesynthesizedbybacteria.Infact,itisthelipopolysaccharideofGram-negativebacteria.Fortheinjectablemedicament,itisespeciallyimportanttoavoidthecontaminationofpyrogeninthecourseofpharmicproduction.

6.Exotoxin：ExotoxinsareproteinsproducedinsideGram-positivebacteriacellsandsecretedintotheenvironment.Thesetoxinsaresomeofthestrongestpoisonsknowntomanandcauseviolentreactionsinhostorganisms.7.Endotoxin：Endotoxinsaremadeupoflipidsandcarbohydratesassociatedwiththeoutermembraneofgram-negativebacteria.Thesetoxinsusuallyproducefever,weakness,andcapillarydamage.8.Disinfection:Reduceoreliminatepathogens病原体inoroninanimate无生命的objectstoasafelevel,whicharenolongerhealthhazard危险.9.Sterilization:Aphysicalorchemicalprocessthatcompletelydestroysorremovesallmicrobiallife，includingbacteriasporeandviruses.10.Antisepsis:Usechemicalagentstoinhibitordestroythegrowthofmicroorganismsonskinorotherlivingtissue.11.Plasmids：Plasmidsaresmallgeneticelementsthatreplicateindependentlyofthebacterialchromosome.Mostplasmidsarecircular,double-strandedDNAmoleculesvaryingfrom1,500to400,000basepairs.LikethebacterialchromosomalDNA,theycanautonomouslyreplicateandassucharereferredtoasreplicons.12.Transformation：ItistheprocessbywhichbacteriatakeupfragmentsofnakedDNAandincorporatethemintotheirgenomes.Duringtransformation,DNAfragmentsfromadeaddegradedbacteriumbindtoDNAbindingproteinsonthesurfaceofacompetentrecipientbacterium.13.Conjugation：ConjugationisthetransferofDNAdirectlyfromalivingdonorbacteriumtoarecipientbacteriumduringthematingofthebacteria.Asexpilusproducedbythedonorbacterium(ormale)bindstotherecipient(orfemale).Thesexpilusthenretracts,bringingthetwobacteriaincontactandthetransferredDNApassesthroughthesexpilus.14.Transduction：Transductionismediatedbyabacteriophage,whichpickupfragmentsofDNAandpackagethemintobacteriophageparticles.TheDNAisdeliveredtoinfectedcellsandbecomesincorporatedintothebacterialgenomes.15.Normalflora:Thevariousbacteriaandfungithatarepermanentresidentsofcertainbodysites,especiallytheskin,oropharynx,colon,andvagina.16.Dysbacteriosis：Iffloradisequilibriumoccurs,forexample,whentheresidentfloraisdisturbed,somelittlesignificantmicroorganismsmaycolonize,proliferateandproducediseases,whicharecalleddysbacteriosis.Dysbacteriosismainlyresultfromlongtermandlargebacteriosismainlyresultfromlongtermandlargebacteriosismainlyresultfromlongtermandlargedosesantibioticstaken.Antibioticscansuppressthedrug-susceptiblecomponentsoffecalflora.Soonthereafterthecountsoffecalflorariseagaintonormalorhigherthannormallevels,principallyoforganismsselectedoutbecauseofrelativeresistancetothedrugsemployed.Thedrugsusceptiblemicroorganismsarereplacedbydrug-resistantonesandcausecorrelativedisease,microbialselectionandsubstitution.17.Toxemia：Bacteriamultiplyatinvadinglocationanddonotenterbloodstream,buttheexotoxinsenterbloodandcausecorrespondingtoxicsymptoms.18.Endotoxemia：Gram-negativebacteriamultiplyatlocationorinbloodstream,releasealotofamountendotoxinreleasedfrombacterialcellrupture.19.ProteinA：ProteinAisacellwallcomponentofmanyS.aureusstrainsthatbindstotheFcportionofIgGmoleculesexceptIgG3.TheFabportionofIgGboundtoproteinAisfreetocombinewithaspecificantigen.ProteinAhasbecomeanimportantreagentinimmunologyanddiagnosticlaboratorytechnology;forexample,proteinAwithattachedIgGmoleculesdirectedagainstaspecificbacterialantigenwillagglutinatebacteriathathavethatantigen(“coagglutination”).ProteinAprobablycontributestothevirulenceofS.aureusbyinterferingwithopsonization.20.Elementarybody（EB）：Elementarybody（EB）aresmallroundcellsabout0.2～0.4μmwithanelectron-densenucleoid.Theypossessacellwall.Theyare

extracellularformandtheenvironmentally

stableinfectiousparticle，andmetabolicallyinactive.TheEBhaveahighaffinityforhostepithelialcellsandrapidlyenterthem，creatingaprotectedmembrane-boundenvironmentaroundthechlamydiae，andtheElementarybodyisreorganizedintoalargeronecalled

metabolicallyactiveReticulatebody（RB）.21.Reticulatebody（RB）：TheintracellularlargeformknownasthereticulatebodyMeasuringabout0.5～1μmanddevoidofanelectron-densenucleoid.Itspresencewillreflectthestageofreplication.Withinthemembrane-boundvacuole，theelementarygrowsinsizeanddividesintorepeatedlybybinaryfission.Eventually，theentirevacuolebecomesfilledwithelementarybodiesderivedfromreticulatebodiestoformacytoplasmicinclusion.Thenewlyformedelementarybodiesmaybeliberatedfromthehostcelltoinfectnewcells.Thedevelopmentalcycletakes24-48hours.22.nucleocapsid：Thesimplestofvirusparticlesconsistsofaproteincoat(capsid)whichsurroundsastrandofnucleicacidandarethuscallednakedvirusesornucleocapsid.23.AbortiveInfections：Notallinfectionsleadtonewprogenyvirus.Productiveinfectionsoccurinpermissivecellsandresultintheproductionofinfectiousvirus.Abortiveinfectionsfailtoproduceinfectiousprogeny,eitherbecausethecellmaybenonpermissiveandunabletosupporttheexpressionofallviralgenesorbecausetheinfectingvirusmaybedefective,lackingsomefunctionalviralgene.24.defectivevirus：Adefectivevirusisonethatlacksoneormorefunctionalgenesrequiredforviralreplication.Defectivevirusesrequirehelperactivityfromanothervirusforsomestepinreplicationormaturation.Onetypeofdefectiveviruslacksaportionofitsgenome(i.e.,deletionmutant).Theextentoflossbydeletionmayvaryfromashortbasesequencetoalargeamountofthegenome.Deletionmutantsmayarisespontaneouslyormaybeconstructedinthelaboratoryusingbiochemicalt