Awiri umuna

Mungu mbewu amene amagwa pa manyazi a mwanjira ina, kuyamba kumera. Mapira zitunda, mungu chubu aumbike kwa maselo vegetative. Choncho, kumera ayamba. Chipolopolo akuswa pa malo thinnest wa mungu chubu. Kuchokera kunsonga ya chubu allocated zinthu zapadera. Iwo kufewetsa nsalu mzati ndi manyazi.

Phata la maselo zobereka ndi vegetative pochitika mu mungu chubu. Zobereka maselo ukugawa ndi ndipamene umuna awiri. Kudzera micropyle (a dzenje mu mthunzi) ovule mungu chubu ndi atagonjetsa mu Ndisanaumbidwe sac. Mkati thumba chubu wasweka ndi nkhani zake anathira.

Ndiye maphatikizidwe amapezeka ndi umuna dzira limodzi. Choncho, zygote, kenako kupereka kuyambira mbewu wosabadwayo. Pamodzi ndi yachiwiri kuphatikiza ndi phata chapakati dontho la umuna. Zimenezi zimabweretsa mapangidwe triploid phata anagubuduza patapita triploid endosperm, ndilo sekondale.

ndondomeko onse pamwamba amatchedwa "awiri umuna zomera maluwa."

Antipodes ndi synergids (kumalo ozizira mtima mu Ndisanaumbidwe sac) nditamaliza ndondomeko ndi kusungunuka, ndi integuments (zophimba) kupanga odula mbewu.

Kawiri umuna zomera anatulukira ndi Russian wasayansi S. Navashin.

Pa ndondomekoyi, phata mu sac embryonic zambiri yokulirapo kuposa phata umuna, amene amayamba ndi kupeza interphase choyamba (wapakatikati gawo). Mu chikhalidwe ichi ndi mawonekedwe a mtima wa mwana wosabadwayo sac zingasiyane. Mwachitsanzo, ena Asteraceae iwo akhoza elongated, nthawi zina tortuous, si nucleoli. Nthawi zambiri, umuna ndi kuperekedwa mu mawonekedwe a mtima anamaliza interphase ndi nucleoli, zina, opanda motsutsana ndi dongosolo la mtima wamkazi.

Kawiri umuna angakhale mitundu iwiri, malinga ndi chikhalidwe cha mgwirizano wa mtima mwamuna ndi mkazi.

Choncho, pamene ndondomeko kumachitika premitotic mtima umuna kumizidwa mu pachimake wamkazi, kumene despiralization (unwinding) DNA. Mwa ichi chimakhazikitsa DNA onse mu mtima interphase anachita.

Postmitotic awiri umuna ndi kulowa mtima mwamuna ndi mkazi, kusunga chipolopolo mu prophase, amene umatha kucheza nawo. Education interphase mtima, amene ali waika khromozomu, akubwera pambuyo akhala akuchita woyamba mitotic kugawikana zygote lapansi.

Pamene awiri umuna akupezeka maphatikizidwe dzira awiri haploid (munali nambala theka DNA) mitima Koma diploid zygote phata (lokhala ndi DNA).

Malinga ndi kuchuluka kwa mtima kumalo ozizira ali selo chapakati aumbike khromozomu chiwerengero cha mtima endosperm.

Kawiri umuna amalimbikitsa makhalidwe anasonyeza ofala mu endosperm mbewu (wosakanizidwa) chomera endosperm wa bambo. Ndi malowedwe a Ndisanaumbidwe sac machubu ochepa mungu, ndondomeko amatenda umuna chubu choyamba, ena machubu umuna yachabechabe. Kawiri umuna ndi awiri spermatozoa ali osowa kwambiri.

Pa zofufuza embryological angapo ntchito oimira angiosperms osiyana (Compositae, Ranunculaceae, Liliaceae) Navashin chowonjezera endosperm zinali monga Ndisanaumbidwe kuti ndondomeko kugonana zomera maluwa. zodabwitsazi ndi khalidwe chabe la oimira angiosperms zomera.

Tikumbukenso kuti ntchito Navashin analola kulongosola bwino funso za chiyambi cha endosperm lapansi. Tanthauzo la zomwe anapeza wasayansi akhala inakulitsidwa.