DURAGAKUNII DIGIBRIDI VA POLIGIBRIDI

Qonuni seyumi Mendel – qonuni kombinatsiyai bevositai genho (novobasta ba meros guzashtani jufti genho) Mendel dar asosi omukhtani merosguzorii yak jufti genhoi alleli bisyor qonuniyathoi genetiki, az jumla, dominanti, tagyir nayoftani allelhoi resessivi dar duragaho, tajziyai alomatho dar naslhoi duragaro bo tanosubi 3:1 isbot namud. Hodisai tajziya nishon dod, ki gametaho az jihati genetiki tozaand, yane az har yak jufti allelho yaktogi gen dorand.

Lekin organizmhoe, ki az yakdigar bo alomathoi bisyor farq mekunand, masalan, du jufti, se juftiyu va beshtar va genhoi onho dar jufti khromosomahoi gomologii gunogun joygirand, bo usuli digibridi va poligibridi muayyan karda meshavand. Duragakunii digibridi gufta duragakuniero menomand, ki agar volidon bo du jufti alomathoi bo ham mukholif (alternativi) az yakdigar farq kunand. Baroi duragakunii digibridi Mendel rastanihoi gomozigotii nakhudro girift, ki bo du jufti genho farq mekunand. In alomat rang (zardu sabz) va shakli donakho (hamvor va chindor) meboshand.

Alomati dominanti rangi zard bo A va shakli hamvori donakho bo V vobastaand. Har yak rastanii volidon yak nav gametaro paydo mekunad va badi omezishi onho dar naslho yakkhelagii alomatho zohir megardad. Dar rafti paydo shudani gametahoi digibridi az har jufti genhoi alleli, ki dar khromosomahoi gomologi joy dorand, tanho yaktoi onho dar gameta joy megirad. Dar in vaqt kashishkhurii khromosomahoi volidon dar taqsimshavii meyozi tasodufi buda, ehtimoliyati vokhurii geni (A) bo geni (V) va geni (v) barobarand. Hamin guna ehtimoliyati vokhuri dar yakjoyashavii geni (a) bo genhoi (V) va (v) meboshad.

Az sababi on, ki dar har organizm gametahoi bisyor paydo meshavand, muvofiqi qonuniyathoi omori dar gibridhoi digeterozigoti chor navi gameta bo miqdori barobar ba vujud meoyand: (25%) AV:Av:aV:av.

Dar rafti bordorshavi har yake az in chor navi gametahoi yak organizm tasodufan bo gametahoi organizmi digar vomekhurand. YAkjoyashavii gametahoi narina va modinaro dar shakli katakcha joygir karda, bo yorii on hisob kardan mumkin ast. In katakcharo katakchai peneti menomand, ki bo nomi olimi anglis R.Penet guzoshta shudaast. Dar jonibi rosti gametaho ufuqi gametahoi narina, dar jonibi chapi amudi gametahoi modina joygirand. Dar katakchaho omezishi gametaho, yane zigotaho va genotipu fenotip navishta shudaand (rasmi 9.3).

Az katakcha ba hisob giriftan mumkin ast, ki az rui fenotip naslho ba chor guruh taqsim shuda, chunin tanosubro paydo mekunand: 9-zardi hamvor, 3-zardi chindor, 3-sabzi hamvor, 1-sabzi chindor. Agar natijai tajziyai har jufti alomat (shakl va rang)-ro dar alohidagi ba hisob girem, pas tanosubi zardu sabz va hamvoru chindor 3:1 meshavad.

Hamin tariq, dar duragakunii digibridi har yak jufti alomat novobasta az hamdigar ba meros guzashta, bo tanosubi tajziyai monogibridi muvofiq ast (12 / zard : 4 / sabz=3 :1, 12 hamvor : 4 chindor = 3:1). Dar vaqti bordorshavi onho muvofiqi qoidai tasodufi omezish yofta, kombinatsiyaho (omezish)-i gunoguni genhoro ba amal meorand.

Taqsimshavii bevositai alomatho dar naslho va paydo shudani kombinatsiyai gunoguni genho, ki inkishofi alomathoro dar duragakunii digibridi muayyan mekunad, faqat hamon vaqt dida meshavand, ki agar jufti genhoi allelii onho dar khromosomahi gayrigomologi joygir shuda boshand.

Qonuni seyumi Mendelro chunin sharh dodan mumkin ast:

Az nasl ba nasl guzashtani jufti alomatho va yo kombinatsiyai jufti genhoi gayri alleli, ki alomathoro nazorat mekunand, novobasta az jufti alomathoi digar ba amal meoyad. Merosguzorii organizmhoi poligibridiro, ki bo se, chor va ziyodtar alomatho az hamdigar farq mekunand, duragakunii poligibridi (bisyorgibridi) menomand. Agar volidon bo se alomat farq kunand, gibridi hosilshudaro trigibrid, bo chor alomat – tetragibrid menomand. Hamin tariq, taj- ziyai alomati monogibridiro donista, tajziyai poligibridiro hisob kardan mumkin ast.

Organizmi geterozigoti Aa du nav gameta 21=A va a, digeterozigoti AaVv-chor navi gameta: 22-AV, Av, aV, av hosil mekunand. Dar trigeterozigotho Aa Vv Ss hasht nav gameta yo ki 23=AVS, AVs, AvS, Avs, aVS, aVs, avS, avs paydo meshavand. Formulai umumii fenotipi poligibridi 2m, meshavad, ki dar in jo n-miqdori jufti genhoi geterozigoti dar genotip meboshad. Formulai umumii genotipi poligibridi 3n ast. Baroi monogibridi 31, (1:2:1). Digibridi Z2 (1:2:1:2:4:2:1:2:1) va gayra (rasmi 9.3).

Metodhoi gibridiologii nishondodai Mendel imkoniyat medihand, ki merosguzorii organizmhoi dominanti va geterozigoti, ki fenotipi dominanti dorand, muayyan karda shavad. Baroi in nasli yakumro bo volidoni gomozigotii       resessivi duraga mekunand. Agar fard gomozigoti dominanti boshad, badi duraga kardan bo gomozigoti resessivi dar gibridhoi nasli G1 yakkhelagii naslho dida meshavad, yane tajziya nameshavand.

Agar fard geterozigoti dominanti va digar gomozigoti retsessivi boshad, on goh dar gibridhoi nasli yakum tajziyai fenotipi bo tanosubi 1:1 yo ki 50:50 ba amal meoyad. CHunin shakli tajziya hangomi duragakuni isbot menamoyad, ki yake az volidon du gameta medihad, yane geterozigoti ast (rasmi 9.4).

Duragakunii tahlilii merosguzorii monogibridi,

A – bunafsh,

a – rangi guli safed

Duragakunii tahlilii fardi digeterozigoti (bo du jufti alomat farq mekunad) chunin ast:

Dar naslhoi gibridii yakum ( F1 ) chor guruhi fenotip bo tanosubi 1:1:1:1 paydo meshavad.

Istilohot:

1. Dominanti – hodisae, ki alleli yak gen alleli geni digarro pakhsh mekunad.
2. Tajziya – dar naslho zohirshavii shaklhoi gunoguni yak alomat.
3. Gomozigot – organizme, ki dar khromosomahoi gomologiashon nukleotidho genhoi yakkhela joygirand.
4. Organizmhoi geterozigoti – fardhoe, ki dar onho allelhoi genho bo paydarhamii nukleotidho farq mekunand.
5. Genotip – sistemai tasiri tarafayni genhoi organizm.
6. Genhoi alleli – genhoe, ki dar joyhoi yakkhelai khromosomahoi gomologi joygirand.
7. Fenotip – majmui hamai alomatho va khosiyathoi organizm.
8. Irsiyat – qobiliyati organizmhoi zinda, ki alomatho va khosiyathoi khudro az nasl ba nasl meguzaronand.

Savolho baroi sanjish:

1. Tajribai Mendelro oidi duragakunii monogibridi va digibridi dar rastanii nakhud fahmoned.
2. Duragakunii tahlili chist? Onro chi tavr dar tahlili merosguzorii alomatho istifoda mebarand?