Tsis tiav dominance yog ib hom tshwj xeeb ntawm kev sib cuam tshuam ntawm cov noob alleles uas qhov tsis muaj zog recessive tsis tuaj yeem cuam tshuam tag nrho los ntawm ib qho tseem ceeb. Raws li cov kev cai lij choj nrhiav pom los ntawm G. Mendel, qhov tseem ceeb ntawm qhov zoo tshaj plaws inhibits qhov tshwm sim ntawm qhov tsis txaus ntseeg. Tus kws tshawb fawb tau kawm hais txog qhov sib txawv ntawm cov nroj tsuag nrog qhov tshwm sim ntawm cov tseem ceeb los yog recessive alleles. Qee zaum, Mendel ntsib qhov tsis ua tiav ntawm tus qauv no, tab sis tsis tau piav qhia rau nws.
New form of inheritance
Qee lub sij hawm, raws li kev hla, cov xeeb leej xeeb ntxwv tau txais cov txiaj ntsig nruab nrab uas niam txiv noob tsis tau muab rau hauv homozygous daim ntawv. Kev tswj hwm tsis tiav tsis nyob hauv lub tswv yim ntawm cov noob caj noob ces kom txog rau thaum pib ntawm lub xyoo pua 20th, thaum Mendel txoj cai tau rov tshawb pom. Nyob rau tib lub sijhawm, ntau tus kws tshawb fawb ntuj tau ua cov kev sim caj ces nrog cov khoom cog thiab tsiaj txhu (txiv lws suav, legumes, hamsters, nas, txiv hmab txiv ntoo yoov).
Tom qab kev pom zoo cytological hauv xyoo 1902 los ntawm W alter Setton ntawm Mendelian cov qauv, cov ntsiab lus ntawm kev sib kis thiab kev sib cuam tshuamCov cim qhia tau pib piav qhia los ntawm qhov pom ntawm tus cwj pwm ntawm chromosomes hauv lub cell.
Nyob rau hauv tib lub xyoo 1902, Cermak Correns tau piav txog ib rooj plaub thaum, tom qab hla cov nroj tsuag nrog dawb thiab liab corollas, cov xeeb leej xeeb ntxwv muaj paj liab - tsis tiav dominance. Qhov no yog ib qho kev tshwm sim nyob rau hauv hybrids (Aa genotype) ntawm ib tug zoo uas yog intermediate nyob rau hauv relation mus homozygous dominant (AA) thiab recessive (aa) phenotypes. Cov txiaj ntsig zoo sib xws tau piav qhia rau ntau hom paj ntoo: snapdragon, hyacinth, hmo ntuj kev zoo nkauj, strawberries.
Tsis tiav dominance - nws puas yog vim li cas rau kev hloov pauv hauv kev ua haujlwm ntawm cov enzymes?
Cov txheej txheem rau qhov pom ntawm peb qhov sib txawv ntawm qhov zoo tuaj yeem piav qhia los ntawm qhov pom ntawm kev ua haujlwm ntawm cov enzymes, uas yog cov proteins, thiab cov noob txiav txim siab cov qauv ntawm cov protein. Ib tsob nroj uas muaj homozygous dominant genotype (AA) yuav muaj cov enzymes txaus thiab cov xim ntawm cov xim yuav zoo li qub rau cov xim ntawm tes.
Nyob rau hauv homozygotes nrog recessive alleles ntawm cov noob (aa), pigment synthesis yog impaired, lub corolla tseem uncolored. Nyob rau hauv cov ntaub ntawv ntawm ib tug nruab nrab heterozygous genotype (Aa), lub tseem ceeb gene tseem tsim ib co pigmentation enzyme, tab sis tsis txaus rau ib tug kaj, saturated xim. Nws hloov tawm xim yog "ib nrab".
Txoj yam ntxwv tau los ntawm hom nruab nrab
Cov qub txeeg qub teg uas tsis tiav yog taug qab zoo ntawm cov yam ntxwv uas muaj qhov sib txawv:
- Xim siv. W. Batson, tau hla dub thiab dawb hens ntawm Andalusian yug,tau cov xeeb ntxwv nrog nyiaj plumage. Cov txheej txheem no kuj muaj nyob rau hauv kev txiav txim cov xim ntawm tib neeg iris.
- Degree ntawm manifestation ntawm tus cwj pwm. Tus qauv ntawm tib neeg cov plaub hau kuj tau txiav txim los ntawm qhov tsis tiav ntawm qhov qub txeeg qub teg ntawm qhov zoo. Lub AA genotype tsim cov plaub hau curly, aa ua cov plaub hau ncaj, thiab cov neeg uas muaj ob qho tag nrho cov plaub hau wavy.
- ntsuas ntsuas tau. Qhov ntev ntawm pob ntseg ntawm nplej tau txais los ntawm lub hauv paus ntsiab lus ntawm kev ua tsis tiav.
Nyob rau tiam F2, tus naj npawb ntawm phenotypes coincides nrog tus naj npawb ntawm genotypes, uas characterizes tsis tiav dominance. Kev txheeb xyuas cov ntoo khaub lig tsis tas yuav txheeb xyuas cov hybrids, vim tias lawv txawv txawv ntawm cov kab ntshiab uas tseem ceeb.
Kev sib cais thaum hla
Kev ua tiav thiab tsis tiav kev tswj hwm raws li kev sib cuam tshuam ntawm noob tshwm sim raws li tus lej lej ntawm G. Mendel txoj cai. Hauv thawj kis, qhov sib piv hauv F2 ntawm phenotypes (3: 1) tsis sib haum nrog qhov sib piv ntawm genotypes ntawm cov xeeb ntxwv (1: 2: 1), txij li phenotypically, kev sib txuas ntawm AA thiab Aa alleles tshwm sim lawv tus kheej hauv tib txoj kev.. Tom qab ntawd tsis tiav dominance yog ib qho coincidence nyob rau hauv F2 feem ntawm txawv genotypes thiab phenotypes (1: 2: 1).
Nyob rau hauv strawberries, xim yog qub txeeg qub teg rau ib xyoos raws li txoj cai ntawm kev ua tsis tiav. Yog hais tias koj hla ib tsob ntoo nrog liab berries (AA) thiab ib tsob nroj nrog dawb berries - genotype aa, ces nyob rau hauv thawj tiam tag nrho cov resulting nroj tsuag yuav muab txiv hmab txiv ntoo nrog ib tug liab xim (Aa).
Tau hla cov hybrids los ntawm F1, hauv qhov thib obtiam F2 peb tau txais qhov piv ntawm cov xeeb ntxwv, coinciding nrog cov genotypes: 1AA + 2Aa + 1aa. 25% ntawm cov nroj tsuag los ntawm tiam thib ob yuav tsim cov txiv hmab txiv ntoo liab thiab tsis muaj xim, 50% ntawm cov nroj tsuag yuav liab.
Peb yuav saib daim duab zoo sib xws hauv ob tiam neeg thaum hla cov kab ntshiab ntawm cov paj ntawm hmo ntuj kev zoo nkauj nrog ntshav thiab dawb corollas.
Txoj kev qub txeeg qub teg thaum tuag ntawm cov noob
Qee zaum, nws nyuaj rau txiav txim siab seb cov noob sib cuam tshuam li cas raws li qhov sib piv ntawm cov noob phenotypes. Nyob rau hauv lub thib ob tiam, splitting nrog tsis tiav dominance txawv ntawm qhov xav tau 1: 2: 1, thiab los ntawm 3: 1 - nrog tag nrho dominance. Qhov no tshwm sim thaum muaj qhov tseem ceeb lossis qhov tsis zoo ua rau muaj phenotype hauv lub xeev homozygous uas tsis sib haum nrog lub neej (cov noob tuag).
Nyob rau hauv grey Karakul yaj, yug menyuam yaj homozygous rau cov xim tseem ceeb allele tuag vim qhov tseeb hais tias xws li ib tug genotype ua rau muaj kev cuam tshuam hauv kev loj hlob ntawm lub plab.
Nyob rau hauv tib neeg, ib qho piv txwv ntawm kev tuag ntawm daim ntawv tseem ceeb ntawm cov noob yog brachydactyly (ntiv tes luv). Qhov zoo yog kuaj pom nyob rau hauv cov ntaub ntawv ntawm ib tug heterozygous genotype, thaum tseem ceeb homozygotes tuag nyob rau hauv thaum ntxov theem ntawm intrauterine kev loj hlob.
Kev tsis txaus ntawm cov noob kuj tuaj yeem ua rau tuag taus. Sickle cell anemia ua rau, nyob rau hauv cov ntaub ntawv ntawm cov tsos ntawm ob recessive alleles nyob rau hauv lub genotype, mus rau ib tug hloov nyob rau hauv cov duab ntawm cov qe ntshav liab. Cov qe ntshav tsis tuaj yeem nqa oxygen tau zoo, thiab 95% ntawm cov menyuam yaus uas muaj qhov tsis zoo no tuag los ntawmoxygen tshaib plab. Hauv heterozygotes, cov hloov pauv ntawm cov qe ntshav liab tsis cuam tshuam rau kev muaj peev xwm zoo li no.
Kev sib cais ntawm qhov muaj cov noob tuag
Thawj tiam, thaum hla AA x aa, kev tuag yuav tsis tshwm, vim txhua tus xeeb leej xeeb ntxwv yuav muaj Aa genotype. Nov yog cov piv txwv ntawm kev sib cais hauv tiam thib ob rau cov neeg mob uas muaj cov noob tuag:
|
Kev xaiv hla Aa x Aa |
tag nrho domination | Tsis tiav domination |
| Lethal allele dominant |
F2:2 Aa, 1aa By genotype - 2:1 By phenotype- 2:1 |
F2:2 Aa, 1aa By genotype - 2:1 By phenotype- 2:1 |
| Txoj kev rov ua kom tsis zoo |
F2: 1AA, 2Aa By genotype - 1:2 Raws li phenotype - tsis sib cais |
F2: 1AA, 2Aa By genotype - 1:2 By phenotype- 1:2 |
Nws yog ib qho tseem ceeb kom nkag siab tias ob qho tib si alleles ua tsis tiav kev tswj hwm, thiab cov txiaj ntsig ntawm ib feem ntawm kev ua phem yog qhov tshwm sim ntawm kev sib cuam tshuam ntawm cov khoom lag luam.
