I-Punnett Square Kuyithuluzi elibalulekile emkhakheni wezakhi zofuzo ukumela ngokucacile inhlanganisela yofuzo engaba khona yenzalo. Yaklanywa uReginald Crundall Punnett ngo-1905, futhi isasetshenziswa izazi zofuzo kanye nezazi zezinto eziphilayo namuhla ukubala amathuba athile ekuweleni kwe-allele.
Lo mdwebo wezibalo wenza kube lula ukuqonda ukuthi ama-alleles avela kubazali bobabili angahlangana kanjani enzalweni yabo. Ithebula lizowela ama-gametes abo bobabili abazali, lihlinzekele kokubili ama-genotypes nama-phenotypes enzalweni.
Sisebenza kanjani isikwele sasePunnett
Isikwele se-Punnett sibonisa imiphumela engaba khona yezinhlanganisela phakathi kwama-alleles abusayo nama-recessive. Ama-allele anamandla amelelwa ngofeleba abakhulu, kuyilapho ama-allele ahlehlayo amelelwa ngofeleba abancane.
Ithuluzi liwusizo ikakhulukazi uma usebenzisa i- Imithetho kaMendel ukubona ukuthi izici zitholwa kanjani kusukela esizukulwaneni kuya kwesinye. Ama-gametes omzali oyedwa aqukethe ikhophi eyodwa ye-allele ngayinye, futhi ngokuwahlanganisa nama-gametes womunye umzali, singakwazi ukubala izilinganiso zama-genotypes futhi, kwezinye izimo, umphumela we-phenotype.
Imithetho kaMendel Iyasebenza ePunnett Square
Imithetho ye UGregor Mendel Bathatha indawo emaphakathi ekusetshenzisweni kwesikwele sasePunnett. Lokhu kuyisihluthulelo sokuqonda ukuthi ama-alleles abusayo futhi aphindaphindayo ahlangana kanjani, nokuthi izici zisakazwa kanjani phakathi kwenzalo. Le mithetho yilena:
- Umthetho wokubusa: ithi lapho i-allele ebusayo ikhona, izosibekela i-recessive, iziveze ku-phenotype.
- Umthetho wokuhlukaniswa: Ama-alleles esici esihlukile ngesikhathi sokwakheka kwe-gamete, okusho ukuthi i-gamete ngayinye iphethe i-allele eyodwa kuphela kusici ngasinye.
- Umthetho wokusabalalisa okuzimele: ama-allele ezakhi zofuzo ezihlukene asakazwa ngokuzimela phakathi kwama-gametes, ngaphandle uma izakhi zofuzo zixhunyanisiwe (ku-chromosome efanayo).
Ukwakha iPunnett Square
Ukudala isikwele se-Punnett kulula futhi kulandela isinyathelo esiyisisekelo ngesinyathelo. Okokuqala, imele a isikwele sihlukaniswe izikwele ezine ezilinganayo. Ama-allele omunye umzali abekwe eduze kwe-eksisi engenhla, futhi lawo omunye abekwe eceleni kwekholomu yesobunxele. Kusuka lapha, amaseli angaphakathi agcwaliswa ngokuhlanganisa ama-allele ahambisanayo ukusuka kumigqa namakholomu.
Isibonelo sakudala kungaba ukuphambana kwabantu ababili abane-heterozygous genotype yesici esilula, esifana nombala wezinwele (Ff). Kulesi simo, isikwele se-Punnett sizobonisa izinhlanganisela ezilandelayo: FF, Ff, Ff, kanye no-ff, ngesilinganiso esingu-3:1 ku-dominant against recessive phenotype.
Ezinye izigigaba zofuzo ngale kwesikwele sasePunnett
Kumele kucatshangelwe ukuthi isikwele se-Punnett, nakuba siwusizo kakhulu, sinemikhawulo. Kukhona izakhi zofuzo eziyinkimbinkimbi kakhulu ezingachazwa kalula yileli thuluzi, njenge Ukubusa futhi i ifa le-polygenic. Endabeni yokubusa ngokubambisana, womabili ama-allele aboniswa ngesikhathi esisodwa, kuyilapho ifa le-polygenic lisikisela ukuthi izakhi zofuzo eziningi zithonya isici esisodwa.
Isibonelo sesiphambano se-dihybrid
Isikwele se-Punnett singanwetshwa ukuze kufundwe iziphambano eziyinkimbinkimbi, njenge-dihybrids, lapho izinhlamvu ezimbili zitholwa njengefa kanyekanye. Kulesi simo, kuzodingeka isikwele se-Punnett samaseli angu-16 esikhundleni sika-4 kuphela.
Cabanga ngecala lakudala likaMendel lapho sihlanganisa khona ubujamo nemibala yamaphizi: kuphi R Yi-allele ehamba phambili yomumo oyindilinga, r I-allele ephindaphindayo yefomu le-rugose, Y Yi-allele evelele yombala ophuzi, futhi y Iyaphindaphindeka kumbala oluhlaza.
Isitshalo ngasinye somzali RrYy ingakhiqiza ama-gametes alandelayo: RY, Ry, rY, ry. Ngokuwela lawa ma-gamete esikwele se-Punnett, sithola isilinganiso sokugcina esingu-9:3:3:1, okubonisa ukuthi ophizi abangu-9 kwabangu-16 bazoba yindilinga futhi baphuzi, 3 bazoba yindilinga futhi babe luhlaza, 3 bazoba nemibimbi futhi baphuzi. , futhi 1 Izoba lukhuni futhi ibe luhlaza.
Lolu hlobo lokuhlaziya lubalulekile ukuze kuqondwe iziphambano eziyinkimbinkimbi kanye namathuba okuthola inzalo ethile lapho izici ezimbalwa zihilelekile ngesikhathi esisodwa.
Ukuhunyushwa kwemiphumela
Uma isiphambano senziwe futhi isikwele sasePunnett sesiqediwe, singahumusha imiphumela. Amaseli kuthebula asinikeza ukumelwa kwazo zonke izinhlanganisela ezingaba khona zama-genotypes enzalweni. Kusuka lapha, singabala amathuba:
- Uma ibhokisi linamaseli amane, ngalinye limelela ithuba elingu-25%.
- Uma ibhokisi linamaseli ayishumi nesithupha, iseli ngalinye limelela u-6,25%
Isikwele se-Punnett singaphinda sisisize sibikezele ukwenzeka kwezifo ezizuzwa njengefa lapho i-genotypes ephindaphindayo ingase imele ingozi. Uma i-genotype ephindaphindayo ihlotshaniswa nesifo, ithebula likuvumela ukuthi unqume ukuthi zingaki izingane ezingase zithwale leso sifo noma zibonise izimpawu.
Izicelo zesikwele sePunnett
Leli thuluzi elilula liwusizo kakhulu emikhakheni eyahlukene:
- Ekufundisweni kwebhayoloji esikoleni nasenyuvesi ukuchaza izisekelo zofuzo.
- Ocwaningweni lwezokwelapha ukuhlola ingozi yofuzo yezifo zofuzo.
- Kusayensi yezolimo ukuthuthukisa izitshalo ngokukhetha inhlanganisela yofuzo evumayo.
Naphezu kokuba lula kwaso, isikwele se-Punnett siyithuluzi elinamandla elivumela izazi zebhayoloji nezazi zezakhi zofuzo ukuba zenze izibalo ezinembile mayelana namathuba efa lofuzo. Le ndlela eyisisekelo isasebenza futhi inikeza isisekelo esiqinile sokuhlaziywa kofuzo kusukela ku-Mendel kuze kube manje.