Ukuphambuka Okubonakalayo Komthetho KaMendel
Ifa likaMendelian, noma izimiso zefa lezakhi zofuzo ezahlongozwa okokuqala nguGregor Mendel, zakha isisekelo sezakhi zofuzo zakudala. Le mithetho ichaza indlela izici ezidluliselwa ngayo kubazali kuya ezinganeni, ngokusekelwe emibonweni yama-allele abusayo nawaphindaphindayo. Kodwa-ke, njengoba ukuqonda kwethu izimo zezakhi zofuzo kujula, kuba sobala ukuthi impilo yangempela ivame ukuphambuka kulezi zindlela ezilula zikaMendelian. Lokhu kudala lokho esikubiza ngokuthi 'okuhlukile okubonakalayo' noma 'okuhlukile okubonakalayo' emithethweni kaMendel.
Ukubuka Okufushane Kwezakhi Zofuzo ZaseMendelian
Ngaphambi kokuhlola lezi zimo ezihlukile, kubalulekile ukuphinda imithetho kaMendel. UMendel waphakamisa izimiso ezintathu eziyinhloko ngokusekelwe ekuhlolweni kwakhe ngezitshalo ze-pea:
1. Umthetho Wokuhlukaniswa: Umuntu ngamunye uphethe ama-allele amabili esakhi sofuzo, ahlukanisa ngesikhathi sokwakheka kwama-gametes.
2. Umthetho Wokuhlukahluka Okuzimele: Izakhi zofuzo zezimpawu ezahlukene ziyahlukana ngokuzimela.
3. Umthetho Wokubusa: Uma kukhona ama-allele amabili ahlukene, enye ingafihla umphumela wenye.
Nakuba le mithetho yakha isisekelo sofuzo, ayibali uhla lwezenzakalo eziphilayo ezibonwa emhlabeni wemvelo.
Uhlobo Lokuphambuka Okubonakalayo
Ukuphambuka okubonakalayo, noma okuhlukile okubonakalayo, kuvela ekusebenzelaneni okuyinkimbinkimbi kwezakhi zofuzo okungabandakanyi imithetho kaMendel. Lokhu okuhlukile kungabangelwa izici ezahlukahlukene zezakhi zofuzo, ezemvelo, noma ze-epigenetic. Ngezansi, sihlola ezinye zezindlela ezivame kakhulu zalezi zihlukile.
Ukubusa Okungaphelele
Ukubusa okungaphelele kwenzeka lapho i-heterozygous phenotype iyingxenye ephakathi kwezinhlobo ezimbili ze-homozygous phenotypes, kunokuba iveze isici esivelele. Isibonelo esivamile umbala wembali kuma-snapdragons, lapho ukuwela i-snapdragon ebomvu nemhlophe kuphumela esizukulwaneni esinezimbali ezipinki. Lesi simo sibonisa ukuthi umqondo wokubusa ngezinye izikhathi ungaba nomqondo ohlukile kunalokho uMendel akuchaze ekuqaleni.
Ukubusa
Ku-codominance, womabili ama-allele kubhangqa lwezakhi zofuzo abonakala ngokugcwele, okuholela esizukulwaneni esine-phenotype esibonisa zombili izici zomzali. Uhlelo lweqembu legazi le-ABO kubantu luyisibonelo esihle. Abantu abane-genotype ye-IAIB baveza ama-antigen amabili e-A ne-B kumaseli abo abomvu egazi, okubonisa i-codominance.
Ama-Allele amaningi
Ukuhlolwa kukaMendel kwakusekelwe kakhulu ezicini ezilawulwa ama-allele amabili. Kodwa-ke, izakhi zofuzo eziningi zinama-allele angaphezu kwamabili, aziwa ngokuthi ama-allele amaningi. Uhlelo lweqembu legazi le-ABO luphinde lusebenze njengesibonelo, lapho uhlobo lwegazi olulawula izakhi zofuzo lunama-allele amathathu ayinhloko: i-IA, i-IB, kanye ne-i.
I-Epistasis
I-Epistasis yenzeka lapho ukuvezwa kwesakhi sofuzo esisodwa kuthonywa yizakhi zofuzo esisodwa noma ngaphezulu, ezingafihla noma ziguqule umphumela waso. Lokhu kungaholela ezilinganisweni ze-phenotypic ezihlukile kulezo ezibikezelwe yimithetho kaMendel. Isibonelo, umbala wejazi kuma-Labrador retrievers uhilela okungenani izakhi zofuzo ezimbili: eyodwa enquma umbala we-pigment kanye nenye elawula ukufakwa kwe-pigment.
I-Pleiotropy
I-Pleiotropy ibhekisela ku-gene eyodwa ethonya izici eziningi ze-phenotypic. Izakhi zofuzo ezinjalo zingadala okuhlukile okubonakalayo emithethweni ye-Mendelian ngokuthonya izici ezahlukahlukene ze-phenotype yesidalwa, ngezinye izikhathi ngezindlela ezibonakala zingahlobene. Isibonelo yi-Marfan syndrome kubantu, lapho ukuguquka kwezakhi zofuzo okukodwa kuthinta isakhiwo samathambo, uhlelo lwenhliziyo nemithambo yegazi, kanye namehlo.
Ifa le-Polygenic
Izici eziningi ziyi-polygenic, okusho ukuthi zilawulwa izakhi zofuzo eziningi. Lolu hlobo lwefa luholela ekushintsheni okuqhubekayo kwezinhlobo zezinto eziphilayo, njengoba kubonakala ezicini ezifana nokuphakama komuntu nombala wesikhumba. Ifa le-Polygenic alihambisani kahle nezimiso zikaMendel, ezichaza ngokuyinhloko izici zezakhi zofuzo olulodwa.
Ukuxhumanisa kanye nokuhlanganiswa kwezakhi zofuzo
Umthetho kaMendel wokwahlukaniswa okuzimele ucabanga ukuthi izakhi zofuzo zitholakala kuma-chromosome ahlukene noma ziqhelelene kakhulu kwi-chromosome efanayo. Kodwa-ke, izakhi zofuzo ezisondelene ngokomzimba kwi-chromosome zingazuzwa ndawonye, into eyaziwa ngokuthi ukuxhumana kwezakhi zofuzo. Ukuhlanganiswa kabusha kungenza lokhu kube nzima nakakhulu, kwethulwe ukuhlanganiswa okusha kwe-allele, ngaleyo ndlela kudale ukuphambuka kusuka kuzilinganiso ezilindelekile ze-Mendelian.
Ezemvelo
Indawo ezungezile ingathonya kakhulu ukubonakaliswa kwe-phenotypic, ngezinye izikhathi ifihle noma iguqule amandla ofuzo. Izici ezifana nokushisa, ukudla okunomsoco, nokukhanya zingashintsha ukubonakaliswa kwezakhi zofuzo, okuholela ekushintsheni okwakungalindelwe yimodeli kaMendel yezakhi zofuzo.
Ukunyathelisa nge-Genomic
Ukunyatheliswa kwezakhi zofuzo kuyisenzakalo se-epigenetic lapho izakhi zofuzo ezithile zivezwa ngendlela ethile yomzali wemvelaphi. Lokhu kusho ukuthi i-allele ezuzwe njengefa kumzali oyedwa ithuliswa ngokwezakhi zofuzo. Izakhi zofuzo ezinyathelisiwe zingaholela ekwehlukeni kokubonakaliswa kwezimpawu kuye ngokuthi i-allele ivela kumama noma kubaba, umqondo ongamboziwe yimithetho yokuqala kaMendel.
Isiphetho
Nakuba okutholwe nguMendel kwabeka isisekelo sokuqonda kwethu izakhi zofuzo, ubunzima bezindlela zofuzo buvame ukuholela ekungahambelani nale mithetho. Lokhu 'kuphambuka okungamanga' kubalulekile ekuqondeni ububanzi obugcwele bokuhlukahluka kwezakhi zofuzo kanye nokwe-phenotypic. Njengoba ucwaningo lwezakhi zofuzo luqhubeka, ubunzima balezi zimo buveza ukwakheka okuyinkimbinkimbi kwezakhi zofuzo, okuthonya amasimu kusukela kwezolimo kuya kwezokwelapha.
Ukuqonda lezi zimo ezihlukile akugcini nje ngokucebisa ukuqonda kwethu ngebhayoloji kodwa futhi kuvusa ilukuluku kanye nomdlandla wokuhlola uhlobo oluguquguqukayo nolunezinhlangothi eziningi lwefa lezakhi zofuzo. Ngakho-ke, ngenkathi imithetho kaMendel inikeza uhlaka olubalulekile, ukuqaphela nokufunda ukulinganiselwa kwayo 'ngokuphambuka okubonakalayo' kunikeza isithombe esibanzi kakhulu sezakhi zofuzo.
