医学遗传学08基因的群体行为engv

《医学遗传学08基因的群体行为engv》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、08基因变异的群体行为PopulationGeneticsWhatisapopulationfromageneticperspective?Apopulationinthegeneticsense,isnotjustagroupofindividuals,butabreedinggroupThegeneticsofapopulationisconcernednotonlywiththegeneticconstitutionoftheindividualsbutalsowiththetransmissionofthegenesfromonegen

2、erationtothenext.Inthetransmissionthegenotypesoftheparentsarebrokendownandanewsetofgenotypesisconstitutedintheprogeny,fromthegenestransmittedinthegametes.Thegenescarriedbythepopulationthushavecontinuityfromgenerationtogeneration,butthegenotypesinwhichtheyappeardonot.Thegenet

3、icconstitutionofapopulation,referringtothegenesitcarries,isdescribedbythearrayofgenefrequencies,thatisbyspecificationoftheallelespresentateverylocusandthenumbersorproportionsofthedifferentallelesateachlocus."GoalsofPopulationGeneticsTodescribehowthefrequencyofanallelewhichco

4、ntrolsatraitchangesovertime；Toanalyzethefactorsthatleadtochangesingene(allele)frequencies；Todeterminehowchangesingene(allele)frequenciesaffectevolutionandspeciation.WhyStudyPopulationsandGeneFrequenciesGeneticvariabilitynecessaryforevolutionarysuccess;Measuringgeneticvariabi

5、lityatmanylocicancharacterizeapopulation;Variabilityofphenotypicandmoleculartraitsareanalyzed.1.VariabilityandGene(orAllelic)FrequenciesGeneticdataforapopulationcanbeexpressedasgeneorallelicfrequencies;Allgeneshaveatleasttwoalleles;Summationofalltheallelicfrequenciesforapopu

6、lationcanbeconsideredadescriptionofthepopulation;Frequenciescanvarywidelyamongtheallelesinapopulation;Twopopulationsofthesamespeciesdonothavetohavethesameallelicfrequencies.GenotypicfrequenciesItdescribesthedistributionofgenotypesinapopulation.ExampleBloodtypelocus;twoallele

7、s,MorN,andthreeMM,MN,NNgenotypesarepossible(thefollowingdatawascollectedfromasinglehumanpopulation).Genotye#ofIndividualsGenotypicFrequenciesMM1787MM=1787/6129=0.289MN3039MN=3039/6129=0.50NN1303NN=1303/6129=0.21Total6129DerivingGene(orAllelic)FrequenciesTodeterminetheallelic

8、frequencieswesimplycountthenumberofMorNallelesanddividebythetotalnumberofal