Easy Genetics: recessive hali - yana da ...

Recessive hali - a irin hali da ba ya bayyana kanta idan akwai wani rinjaye allele genotype na wannan alamar. Don fahimtar wannan definition, bari magance hanyar da coding ãyõyi faruwa a kayyade matakin.

A bit da ka'idar

Kowane alama a cikin mutane da aka sauya ta biyu kwayoyin halitta, alleles, daya daga kowane iyaye. Alleles kasu kashi rinjaye da kuma recessive. Idan wani gamete akwai rinjaye da kuma recessive allele, da phenotype zai bayyana rinjaye. Wannan manufa misalta wani sauki misali na makaranta hanya na nazarin halittun idan iyaye daya blue ido, da kuma sauran - launin ruwan kasa, sa'an nan da yaro yake iya zama ruwan kasa idanu, kamar yadda blue - recessive hali. Wannan mulki da aka jawo idan a cikin genotype na biyu ruwan kasa-sa ido iyaye m allele rinjaye. Bari ruwan kasa idanu ga amsoshin A gene for blue - a. Sa'an nan, a lokacin da ya ketare da dama yiwu zaɓuɓɓuka:

P: AA x aa;

F1: Aa Aa Aa Aa.

All heterozygous zũriyarmu, kuma duk bayyana rinjaye - launin ruwan kasa idanu.

Na biyu zaži:

P: Aa x aa;

F1: Aa, Aa, aa, aa.

Tare da wannan ketare da kuma bayyana a recessive hali (wannan blue idanu). A yiwuwa cewa wani yaro zai kasance a blue-sa ido, - 50%.

Hakazalika gaji zabiya (pigmentation cuta), da makanta, hemophilia. Wannan recessive halaye na mutum, wanda ya bayyana ne kawai a cikin rashi na wani rinjaye allele.

Features recessive dabiu

Mutane da yawa recessive halaye sun taso a sakamakon kwayoyin maye gurbi. Ka tuna, misali, da kwarewa na Thomas Morgan tare da 'ya'yan tashi Drosophila. A al'ada ido launi for kwari - ja da wasu fari-sa ido kwari sabili da aka maye gurbi a kan X chromosome. Kuma akwai wani recessive, jima'i-nasaba.

Hemophilia A, da makanta, kuma ya kamãta da recessive dabiu, jima'i-nasaba.

La'akari tsallaka recessive dabiu misali launi makanta. Zaton cewa gene alhakin al'ada launi ji, - X, a mutant - X ^d. Crossbreeding ne kamar haka:

P: XX X X ^d Y;

F1: XX ^{d, d} XX, XY, XY.

Wannan shi ne, idan uba na ne launi makafi, kuma uwarsa a lafiya mai kyau, duk yara za su zama lafiya, amma 'yan mata za su zama yan dako na launi makanta gene, wanda yake shi ne 50% damar da za a nuna a cikin su maza. Mata colorblindness ne sosai rare, saboda lafiya X chromosome Rama ga mutant.

Sauran iri gene hulda

A baya misali da launi da idanu - wani misali na jimlar mamayar, cewa shi ne, da rinjaye gene ne gaba daya drowns fitar da recessive gene. Alama bayyana a cikin genotype yayi dace da rinjaye allele. Amma akwai sau lokacin da rinjaye gene ba gaba daya cike da recessive, da kuma zuriya da aka nuna a giciye - wani sabon fasalin (kodominirovanie), ko bayyana kansu duka biyu genes (bai cika dominance).

Kodominirovanie - a rare sabon abu. A cikin mutane kodominirovanie bayyana kawai gādon jini kungiyoyin. Bari daya daga cikin iyaye na biyu rukuni na jini (AA), na biyu - na uku kungiyar (BB). Duka A da B halayyar rinjaye. Lokacin da ya haye, mun sami cewa duka yara da jini hudu kungiyar, masu lamba kamar yadda AB. Wannan shi ne bayyanannu a cikin phenotype na biyu ãyõyi.

Har ila yau, sun gaji launi na da yawa flowering shuke-shuke. Sa'ad da kuka haye ja da fari rhododendron, sakamakon na iya zama duka ja da fari da kuma bi-launi flower. Ko da yake jan shi ne rinjaye, da kuma a cikin wannan hali, ba kashe da recessive hali. Wannan hulda a wadda biyu halaye bayyananne daidai vigorously genotype.

Wani sabon abu misali ne alaka kodominirovaniem. By tsallaka ja da fari halittu a sakamakon iya zama ruwan hoda. The m launi ne a sakamakon bai cika dominance, a lokacin da rinjaye allele interacts da recessive. Saboda haka, wani sabon matsakaiciyar fasalin.

ba-allelic hulda

An sadãki cewa mutum genotype bai cika dominance ba peculiar. bai cika dominance inji shi ne ba zartar da launi gādo. Idan daya daga cikin iyaye na fata ne duhu, da sauran haske, kuma da yaron - duhu, matsakaici zaɓi, shi ne ba da wani misali na bai cika dominance. A wannan yanayin kawai ya faru hulda nonallelic genes.