Ntau tus ntawm peb tau hnov txog cov noob caj noob ces tseem ceeb - qee cov chains ntawm nucleotides zais rau hauv peb cov genome uas yog lub luag haujlwm rau kev xeeb tub. Lawv sib cuam tshuam li cas? Dominance yog dab tsi thiab nws tshwm sim li cas? Yog vim li cas recessive alleles tsis ib txwm suppressed los ntawm cov tseem ceeb? Cov lus nug no tau tuav cov kws tshawb fawb txij li tshawb pom cov noob.
Tshawb nrhiav keeb kwm
Kev sib cuam tshuam ntawm alleles ib txwm muaj kev txaus siab rau cov noob caj noob ces. Hauv chav kawm ntawm kev tshawb fawb, nws tau pom tias muaj ntau hom kev sib cuam tshuam ntawm noob - ua tiav dominance, overdominance, ntau yam allelism, tsis tiav dominance thiab codominance.
Txoj cai hu ua leej txiv ntawm cov noob caj noob ces niaj hnub no, Gregor Mendel yog thawj tus xav paub txog cov cai ntawm kev sib kis ntawm cov noob caj noob ces. Nyob rau hauv cov chav kawm ntawm nws nto moo thwmsim ntawm hybridization ntawm peas nroj tsuag, Mendel pom tias hla daj thiab ntsuab peas tsis ua rau ib tug nruab nrab zoo. Hauv thawjtiam, tag nrho cov peas tau daj. Mendel nws tus kheej tom qab ntawd tsis tuaj yeem piav qhia cov txiaj ntsig ntawm nws qhov kev sim ua tau zoo. Lub hauv paus theoretical tau tshwm sim ntau tom qab, tom qab lub rooj txhawb siab ntawm kev txaus siab ntawm noob caj noob ces thiab kev tshawb pom ntawm lub tsev kawm theem pib ntawm kev xeeb tub - cov noob. Nws nyob ntawm nws cov xim ntawm cov txiv laum huab xeeb, lub qhov ntswg, xim ntawm lub qhov muag, qhov siab, muaj kab mob hauv tib neeg.
Cia peb rov qab mus rau Mendel qhov kev sim. A gene yog lub luag haujlwm rau xim daj ntawm peas, thiab cov noob rau xim ntsuab. Thaum hla ob txoj kab ntshiab sib txawv, kev sib cais yuav ua raws li hauv qab no:
R: AA x aa
F1: Aa Aa Aa Aa
Txawm hais tias nyob rau hauv lub genotype ntawm tag nrho cov nroj tsuag tshwm sim muaj ib tug noob rau daj thiab ntsuab, thaum kawg tsuas daj tshwm. Hauv lwm lo lus, qhov tseem ceeb tshaj plaws tau poob dej tawm ntawm qhov rov qab. Nyob rau hauv tib txoj kev, cov duab ntawm peas tau txais txiaj ntsig - du prevailed tshaj wrinkled. Nws yog qhov piv txwv no uas qhia txog kev ua tiav ntawm cov noob - kev tawm tsam ntawm qhov kev coj cwj pwm tsis zoo los ntawm qhov tseem ceeb ntawm ob qho tib si hauv genotype.
Piv txwv ntawm kev ua tiav tag nrho
Hla cov nroj tsuag ntawm cov xim sib txawv tsis yog thaj chaw nkaus xwb uas muaj kev ua tiav tiav. Piv txwv ntawm hom kev sib cuam tshuam no kuj tuaj yeem raug suav los ntawm thaj chaw ntawm tib neeg caj ces: yog tias ib tus niam txiv muaj qhov muag xim av, qhov thib ob muaj qhov muag xiav, thiab ob qho tib si yog homozygous rau cov yam ntxwv no, ces txhua tus menyuam yuav muaj qhov muag xim av.
Ib yam li ntawd, muaj qhov pom ntawm Rh yam, polydactyly,freckles, cov plaub hau tsaus xim. Tag nrho cov cwj pwm no yog qhov tseem ceeb thiab yuav tsis tso cai rau cov phenotype tshwm sim.
Txoj kev tswj hwm yog qhov tseem ceeb hauv kev ua qub txeeg qub teg ntawm cov kab mob caj ces. Feem ntau ntawm lawv (Tay-Sachs tus kab mob, Urbach-Wite kab mob, Gunther's disease) tau txais los ntawm autosomal recessive yam, uas yog, yog hais tias tus genotype muaj ib txwm (tseem ceeb) noob, cov mutant allele yuav tsis tshwm sim nws tus kheej.
About dominance tsis tiav
Tsis tiav dominance yog ib hom kev sib cuam tshuam ntawm noob, feem ntau pom nyob rau hauv qhov xwm txheej. Nrog nws, qhov recessive allele tsis yog kiag li suppressed los ntawm tus tseem ceeb, thiab ib tug tshiab, nruab nrab zoo tshwm sim nyob rau hauv lub phenotype. Ib qho piv txwv zoo ntawm kev ua tiav tsis tiav yog qhov xim ntawm cosmos paj. Yog hais tias koj hla ib tsob ntoo liab nrog ib tug dawb, ces nyob rau hauv thawj tiam cov phenotype splitting yuav raws li nram no: 1 (AA): 2 (Aa): 1 (aa). Ntawd yog, ib lub paj yuav liab, ib qho dawb, thiab ob lub paj liab. Cov yav tas yog ib qho piv txwv ntawm tsis tiav dominance, txij li thaum lub dominant zoo, liab, tsis kiag li suppress lub recessive ib. Raws li qhov tshwm sim, kev cuam tshuam ntawm ob lub noob tau tshwm sim hauv lub cev.
Tsis tiav dominance yog ib txwm tsis yog rau cosmea xwb, tab sis kuj rau ntau lwm cov paj: snapdragons, tulips, carnations.
Nyob zoo
Kev Tshaj Tawm yog qhov nthuav thiab qee yam tsis sib xws ntawm cov noob kev sib cuam tshuam, uas cov noob tseem ceeb hauv phenotype ntawm cov kab mob heterozygous (BB) tshwm sim nws tus kheej ntau dua li hauv phenotype ntawm homozygote (BB). Overdominance tsis tshwm sim hauv qhov xwm txheejfeem ntau ua tiav dominance. Ib qho piv txwv yog kev hloov pauv hauv HBB gene, uas txo qhov kev pheej hmoo ntawm tus kab mob malaria.
kev sib koom siab
Muaj ntau ntau lwm yam kev sib cuam tshuam ntawm noob, thiab ib qho ntawm lawv yog kev sib koom ua ke. Nyob rau hauv cov ntaub ntawv no, tus tseem ceeb allele tsis npog los yog suppress lub recessive ib, thiab ob qho tib si zoo tshwm sim lawv tus kheej mus rau ib tug tej yam kev mob nyob rau hauv lub phenotype.
Txoj hauv kev yooj yim tshaj plaws kom nkag siab qhov tshwm sim ntawm kev sib koom ua ke yog qhov piv txwv ntawm paj liab-dawb ntawm rhododendron, lossis kev zoo nkauj hmo ntuj. Cov xim no tau txais los ntawm kev hla cov paj liab thiab dawb, thiab txawm hais tias cov xim liab yog qhov tseem ceeb, nws tsis poob tawm ntawm allele lub luag haujlwm rau xim dawb. Qhov no yog qhov txawv ntawm ob xim paj nrog Aa genotype tau txais.
Ib qho piv txwv ntawm kev sib koom ua ke yog cov txheej txheem ntawm kev xeeb tub ntawm pawg ntshav. Cia ib niam txiv muaj cov ntshav thib ob (IAIA), thiab tus thib ob muaj peb (IВ IB), ces tus me nyuam yuav muaj pawg plaub, uas tsis yog nruab nrab ntawm qhov thib ob thiab thib peb, nrog cov genotype IA IB.
