Dunmiiqa - waa ... Description, qaab-dhismeedka iyo shaqada

qeybinta dunmiiqa - dhisme ku meel gaar ah la sameeyay inta lagu guda jiro geeddi-socodka maytosis iyo meiosis, iyo bixinta kalasaar koromosoom iyo qeybinta unug. Waxaa cirifoodka: Nidaamka microtubule sameeyay bannaan oo u dhaxeeya ulihiina, qaabka dunmiiqa ah. Gobolka centromere ee kinetochores koromosoom ku xiran yihiin microtubules dunmiiqa. Sida laga soo xigtay isaga si koromosoomyada ka gudbaan ulaha.

Qaab-dhismeedka

Dunmiiqa ka kooban yahay saddex walxaad aasaasiga ah dhismaha: microtubules, koromosoomyada iyo qeybinta ulaha. Pole qaybinaya xayawaanka waxaa lagu abaabulay via centrosome ah, kuwaas oo ka kooban centrioles. In the case of meelaha aan centrosomes (in dhirta, iyo in oocytes ee noocyada qaar ka mid ah) dunmiiqa ayaa cirif ah ballaaran oo u yeedhay atsentrosomalnym. In formation of dunmiiqa lug waa qaab kale - borotiinada motor. Waxay ka tirsan tahay dynein iyo kinesin.

qeybinta dunmiiqa - dhismeedka a-cirifoodka. Labada ulo ku yaalaan centrosomes - organelles in ay yihiin xarumaha ururka microtubule. Dhismaha centrosome kala laba centrioles, kuwaas oo ku hareereysan dad badan oo la borotiin oo kala duwan. koromosoomyada koobat isagoo qaab laba chromatids wada qabtay goobta centromere, oo ku yaalla inta u dhaxaysa ulaha. In centromeres waa kinetochores, taas oo qaadataa meel lifaaqa ah ee microtubules.

formation

Tan iyo dunmiiqa qeybinta - waa qaab in mas'uul ka yahay qeybinta unug, laga bilaabo ay shirka ka dhacdaa prophase. In dhirta iyo oocytes ay ka maqan yihiin centrosomes, xarunta abaabulka microtubule adeegtaa sida qolof ah xuduntii. Microtubules u dhow baqshadda nuclear yihiin iyo dhamaado prophase soo daahay ay hanuuninta, iyo foomka "dunmiiqa prophase" - dhidibka dunmiiqa mustaqbalka.

Sababo la xaqiiqada ah in unugyada xayawaanka waxaa centrosome ka door ee ururka ee xarunta, bilowgii formation of dunmiiqa mitotic waa farqi ah oo u dhexeeya labada centrosomes inta lagu guda jiro prophase. Tani waa suurto gal, maxaa yeelay, borotiinada motor ka dynein ay ku xiran yihiin in ay dusha sare ee asaasiga ah iyo dhinaca gudaha ee xuubka unuga. Kooxda dynein lifaaqan xuub, ku xiran microtubules xidiguhu oo ay bilaabaan in ay u guuraan dhamaadkii negative, ay sabab u tahay taas oo ay jirto Barxo of centrosomes goobaha horjeeda ee xuubka unuga.

dhamaadka shirka

Aasaasidda final of dunmiiqa dhacdaa marxalad prometaphase, ka dib markii lumis ee xuub waxa uu noqonayaa core dhamaystiran, maxaa yeelay, waa markaas centrosomes iyo microtubules heli kartaa helitaanka qaybaha of dunmiiqa.
Si kastaba ha ahaatee, waxaa jira hal marka laga reebo: gaysashada formation dunmiiqa mitotic khamiirka dhacdaa gudahood xuduntii.

Thread formation dunmiiqa iyo hanuuninta waa wax aan macquul aheyn oo aan laba hannaan: ururka of microtubules agagaarka koromosoomyada oo ay xidhiidh la midba midka kale ee ulaha soo horjeeda ee horyaalka. Qaar badan oo ka mid ah waxyaabaha lagama maarmaanka u ah formation of final dunmiiqa, oo ay ku jiraan koromosoomyada iyo borotiinada motor helay gudaha bu'da unugga, iyo microtubules iyo, haddii centrosomes cell xayawaanka ku jira cytoplasm ah, i.e., qaybaha waxaa go'doonka ka ah midba midka kale. Taasi waa sababta formation of dunmiiqa dhamaado kaliya ka dib markii lumis ee baqshadda nuclear.

ku biiro koromosoomyada

In formation of protein dunmiiqa mitotic waa qayb, iyo sidoo kale dhismayaasha kale oo badan, iyo habka this ayaa sidoo kale bartay in unugyada xayawaanka. Inta lagu guda jiro prophase, microtubules sameeyaan agagaarka dhismaha centrosome stellate oo diverges jihada radial. Ka dib markii nasashada xuub nuclear hoos, xasilooni firfircoon ee microtubules bilaabaan inay si firfircoon uga sahamin deegaanka iyo kinetochores of koromosoomyada la hagaajin karin iyaga. Qaar ka mid ah qayb ka mid ah koromosoom dhakhso Ieh ee ulaha ka soo hor jeedda, oo xidho haray first to microtubules mid ka mid ah ulaha laga gelin lahaa, ka dibna kaliya ay bilaabaan inay u guurto dhinaca baallaha midig. Marka geeddi-socodka la dhamaystiro, ee koromosoom, mar hore la xiriira wax kinetochores bilowga pole lifaaq microtubules ka ulo ka soo horjeeda, si ay inta ay socoto metaphase in kinetochores ku xiran yahay inta u dhaxaysa toban iyo afartan tuubooyinka. formation Tan waxaa lagu magacaabaa dogob kinetochore ah. Tartiib tartiib koromosoom kasta waxa uu la xidhiidhaa cirif ka soo hor jeedda, oo waxay loo sameeyay in qaybta dhexe ee saxanka metaphase dunmiiqa.

Habka labaad

Waxaa waa xaalad kale oo taas dunmiiqa la abuuri laga yaabaa in qeybinta. Waxa kale oo suuragal ah in unugyada isagoo centrosome ah, iyo unugyada, taas oo ay ka maqan yihiin. Geedi socodka ku lug adag giraanta tubulin gamma ah, ay sabab u tahay taas oo ay jirto nucleation gaaban microtubules agagaarka koromosoomyada ah. Tuubooyinka ku lifaaqan ka-daray-dhamaadka kinetochore, ka dib markii taas polymerization ee microtubules bilaabmaa, in uu yahay, koritaanka gacanta. darfihiisa xun oo ka mid ah "ku milmaan" oo ay ku hadhaan kala qeybinta sabab u ulo borotiinada motor. Haddii formation of dunmiiqa lug labo ka mid ah centrosomes, waxa uu fududeeyaa xidhiidhka ka mid microtubules, laakiin habka suurto gal ah iyaga oo aan.

si siman

separation A cad u dhexeeya labada koromosoomyada unugyada ahaan inta lagu jiro fission, dhici kartaa oo keliya haddii chromatids aaday kinetochores ay soo biiray in ay ulaha kala duwan. chromatids Meelaan-cirifoodka waxaa lagu magacaabaa amfitepicheskogo, laakiin waxaa jira fursado kale oo ka kici waqtiga dunmiiqa qeybinta labada socday. monotepicheskoe Tani (mid kinetochores lifaaqan mid pole) iyo sintepicheskoe (labada koromosoomyada kinetochore ku xiran yihiin hal pole). Marka merotepicheskom mid kinetochore waxaa u dabin ah laba ulaha. Ma deggan caadiga ah, bond-cirifoodka oo kaliya in uu dhacaa sabab u tahay ciidamada xiisad ka ulihiina ah, hababka kale ee lagala kulmo waa deganayn iyo karo, laakiin waxaa laga yaabaa in ay sabab u tahay meesha uu kinetochore ah.