细菌的遗捅湟3细菌的遗传和变异aspan 课件

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1、Bacterialgenetics&variationKeyWordsChromosomesPlasmidTransposonBacteriophageLyticorVirulentPhagesLysogenicorTemperatePhagePlaqueassayMutationsGenetransfer:(orgeneticexchange)Transformation:Transduction:Conjugation:Lysogenicconversion:Protoplastfusion:Generec

2、ombination：Bacterialgenetics1.Genetics：definesandanalyzesheredity(constancy)andchangeinthevastarrayofphysiologicfunctionsthatformthepropertiesoforganisms.2.Mutations:areheritablechangesinthestructureofgenes.BacterialgeneticmaterialsGenome/Chromosomes:Thecomp

3、letesetofinstructionsformakinganyorganismiscalleditsgenome.Acopyofthegenomeisfoundineachbacterialcell,anditconsistsoftwotightlycoiledthreadsofdeoxyribonucleicacid(DNA)organizedintostructurescalledchromosomes.Gene:BasesBacterialchromosomePlasmid:plasmidsareub

4、iquitousextrachromosomalelements,composedofdouble-strandedDNAthattypicallyiscircular.plasmidscarrygenesassociatedwithspecializedfunctions.BacterialgeneticmaterialsBacterialDNAPlasmidGeneralPropertiesofPlasmidsAsingleorganismcanharborseveraldistinctplasmids.R

5、eplicateindependentlyfromchromosome.PlasmidsvarygreatlyinsizePlasmidsvarygreatlyinthemodeofcontroloftheirreplication,ThemajorplasmidsFertilityplasmid(Ffactor)-------conferredoncellstheabilitytotransferbacterialchromosomegenestorecipientcells.Bacteriocinogeni

6、cplasmids----Theseplasmidshavegeneswhichcodeforsubstancesthatkillotherbacteria.Resistanceplasmids(Rfactor)-----Theseplasmidscarryantibioticresistancegenes.ConjugationplasmidTheAmericangeneticistBarbaraMcClintockdiscoveredthroughherstudyofthegeneticofcornthat

7、somegeneshavetheabilitytomovefromonechromosometoanother,thusproducevariabilityinphenotypicexpressionthatdoesnotadheretoclassicMedelianratiossincetheinsertionofsuchsegmentsturnsgenesforcoloronandoff. ShecalledthesesegmentsofDNAtransposablegeneticelements(tran

8、sposons)or,morecommonly,"jumpinggenes."McClintockwontheNobelPrizeforherdiscovery.TransposableElementBacterialgeneticmaterialsTransposableElement:aregeneticunitsthatarecapableofmediatingtheirownt