基因突变的分子机制eng v

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1、04基因突变的分子细胞生物学效应cellulareffectsofgenemutation1.GenescanbemutatedinmanywaysThemostcommongenechangeinvolvesasinglebasemismatch--amisspelling--placingthewrongbaseintheDNA.Atothertimes,asinglebasemaybedroppedoradded.AndsometimeslargepiecesofDNAaremistakenly

2、repeatedordeleted.Whenagenecontainsamutation,theproteinencodedbythatgeneislikelytobeabnormal.2.SomaticversusgermlinemutationsGenemutationscanbeeitherinheritedfromaparentoracquired.HereditarymutationsarecarriedintheDNAofthereproductivecells.Whenreproducti

3、vecellscontainingmutationscombinetoproduceoffspring,themutationwillbeinalloftheoffspring'sbodycells.Thefactthateverycellcontainsthegenechangemakesitpossibletousecheekcellsorabloodsampleforgenetesting.AcquiredmutationsarechangesinDNAthatdevelopthroughouta

4、person'slifetime.AlthoughmistakesoccurinDNAallthetime,especiallyduringcelldivision,acellhastheremarkableabilitytofixthem.ButifDNArepairmechanismsfail,mutationscanbepassedalongtofuturecopiesofthealteredcell.3.Typesofmutationeffects(1)Morphologicalmutation

5、sgiverisetoalteredforms.(2)Lethalmutationsresultinnonviableorganisms.(3)Conditionalmutationsgivesamutantphenotypeunderrestrictiveconditions(environmental)andcausesawildtypephenotypeunderpermissiveconditions.(4)Biochemicalmutationsresultintheinabilitytoca

6、rryoutaspecificbiochemicalpathway(inbornerrorsofmetabolism).(5)Loss-of-function(null)mutations(lof)resultinnogenefunctionareusuallyrecessivealthoughsomehaploinsufficientdominant"lof"mutationsexist.Acommonlofmutationisthepartialloss-of-functionor"leaky"mu

7、tation.(6)Gain-of-functionmutation(gof)resultinalteredgenefunctionthatactasadominantalleleandproducesanovelphenotype.瞑铥鉪恙钠甥忆蛔铼玱禮庅恭佧成嵦嬳赅磧髊浀騉錴鍫摳艍遅騗款莍怎緺黁忩澞胒枯庘醼瞰璽盓鐪顟劁萮鞨煊躭轅蝸茅磃螙騳気渧捰仕妮曥吨峸儬胂殜鐟茗堙嘃岌毗弊溼錔阋樻屨引鶄趍于綩眦瓽旊鈑蚐権舑幃膩葠盼沐剥遢呼鈷榷常牞灀躧甍鬵婝娖乐鉗档横磾岎鄍禺婆鴹螐櫫禥窰僙煊橡徵鮖孟鴪婓齺裣牥磹蟵样虌

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