Uthi lokuphotha - kungcono ... Incazelo, lokuphatselene nesakhiwo nemsebenti

division Uthi lokuphotha - isakhiwo sesikhashana imiswe phakathi lwe-mitosis futhi meiosis, nokunikeza chromosome ukuhlukaniswa futhi cell division. It okuguquguqukayo: microtubule uhlelo kwakheka isikhala phakathi Kuma-pole, ukuma uthi lokuphotha. Isifunda centromere chromosome kinetochores Banamathele microtubules uthi lokuphotha. Ngokusho kwakhe kuma-chromosome uphokophele izingongolo.

isakhiwo

Uthi lokuphotha inezigaba ezintathu eziyisisekelo kwesakhiwo: microtubules, ama-chromosome nokuhlukana izingongolo. Pole sokuhlukanisa izilwane ihlelwe nge centrosome, aqukethe centrioles. Endabeni izindawo ngaphandle centrosomes (ezitshalweni, futhi oocytes kwezinye zezinhlobo) uthi lokuphotha has nesigxobo ububanzi futhi ngokuthi atsentrosomalnym. Ngo ukwakheka lokuphotha abathintekayo kungenye isakhiwo - motor amaprotheni. Basonta dynein futhi kinesin.

division Uthi lokuphotha - isakhiwo okuguquguqukayo. Bobabili izingongolo zitholakala centrosomes - organelles ukuthi kukhona izikhungo microtubule inhlangano. Isakhiwo centrosome ukuhlukanisa centrioles ezimbili, okuyinto zizungezwe uquqaba amaprotheni ezahlukene. Ama-chromosomes e-Condensed, isimo sanoma chromatids ezimbili labetibambile ndawonye ngesikhathi centromere site, elise phakathi izingongolo. Esikhathini centromeres kukhona kinetochores, eyabe isifika ukunamathela microtubules.

kumiswa

Njengoba ukuhlukana lokuphotha - isakhiwo ukuthi unesibopho cell division, ekuqaleni umhlangano walo kwenzeka prophase. Ngo izitshalo futhi oocytes ngokungabi bikho centrosomes, microtubule ekuhlelweni isikhungo ukhonza njengelungu igobolondo le-nucleus. Microtubules abasondelene imvilophu yenuzi futhi iphela prophase ngasekupheleni ukwaziwa kwawo, futhi yakha "lokuphotha prophase" - esizayo lokuphotha axis.

Ngenxa yokuthi kumaseli Isilwane le centrosome udlala indima inhlangano isikhungo, ekuqaleni kumiswa lokuphotha mitotic kuyinto iphutha phakathi centrosomes ezimbili ngesikhathi prophase. Lokhu kungenzeka ngoba namaprotheni motor dynein basuke enamathiselwe ebusweni elingaphandle umnyombo futhi ohlangothini engaphakathi ulwelwesi cell. dynein iqembu enamathiselwe ulwelwesi, exhunywe ne microtubules astral baqala ukuthutha ngasekupheleni negative, ngenxa okuyinto kukhona dilution ka centrosomes ezizindeni okuphambene ulwelwesi cell.

Ukuphela inhlangano

Ukwakheka sokugcina lokuphotha kwenzeka ngesikhathi isigaba prometaphase, emva ukunyamalala ulwelwesi iba core ephelele, ngoba ngaleso sikhathi centrosomes futhi microtubules angathola ukufinyeleleka yezingxenye uthi lokuphotha.
Nokho, kukhona omunye ngaphandle: i luthela imvubelo mitotic lokuphotha kumiswa kwenzeka ngaphakathi kuyi-nucleus.

uhala kumiswa lokuphotha ukuthambekela yabo akunakwenzeka ngaphandle izinqubo ezimbili: inhlangano microtubules emhlabeni-chromosomes nebudlelwano bawo nomunye izingongolo okuphambene ukuhlukana. Abaningi izakhi ezidingekayo ukuze kumiswa sokugcina othini lokuphotha, kuhlanganise-chromosomes motor amaprotheni atholakala ngaphakathi kuyi-nucleus yengqamuzana, futhi microtubules futhi, uma centrosomes iseli isilwane eziqukethwe cytoplasm, ngamanye amazwi, izingxenye behlukene. Yingakho kumiswa uthi lokuphotha iphela kuphela emva ukunyamalala imvilophu zenuzi.

ngokujoyina-chromosomes

Ngo ukwakheka mitotic lokuphotha amaprotheni kuhileleke, kanye nezinye izakhiwo eziningi, futhi le nqubo ibilokhu wafunda kahle amaseli isilwane. Phakathi prophase, microtubules yakha emhlabeni centrosome stellate isakhiwo esingagcina siyahluka esiqondisweni osabalalayo. Ngemva zenuzi ulwelwesi amakhefu phansi, ukungazinzi ngokwezomnotho othakazelisayo microtubules uqale ngenkuthalo ukuhlola le ndawo futhi kinetochores wama-chromosomes ingalungiswa kubo. Ezinye ingxenye chromosome ngokushesha uyaphenduka lapho ezwa izingongolo okuphambene, kanye asele bophezela ngowokuqala microtubules omunye nezingodo futhi kuphela ke baqala iphokophele isigxobo kwesokudla. Lapho inqubo usuphothuliwe, kuma-chromosome, kakade ehambisana nanoma iyiphi isiqalo kinetochores isigxobo babiza microtubules kusukela izingongolo okuphambene, ukuze phakathi kwenqubo metaphase ukuba kinetochores ixhunyiwe phakathi amashubhu eziyishumi amane. Lokhu kumiswa libizwa ugongolo kinetochore. Kancane kancane chromosome ngayinye lihlotshaniswa isigxobo obuhlukile, futhi akhiwa ingxenye ephakathi nendawo yendlela esakha lokuphotha metaphase ipuleti.

Eyesibili inketho

Kunenye isimo lapho kungenzeka uthi lokuphotha kwakhiwa division. Kungenzeka futhi amaseli kokuba centrosome, futhi amaseli lapho bengekho. Le nqubo ihlanganisa i-gamma tubulin indandatho eziyinkimbinkimbi, ngenxa okuyinto kukhona nucleation esifushane microtubules emhlabeni chromosome. Amashubhu exhunywe kinetochore-plus-ekupheleni, okwathi ngemva kwalokho polymerization of microtubules iqala, okungukuthi, ukukhula elawulwa. imikhawulo Negative we "Hlanganisa" futhi bahlale division ngenxa motor amaprotheni izingongolo. Uma kumiswa lokuphotha abathintekayo yebhangqa centrosomes, kwenza kubelula ukuxhumana microtubules, kodwa inqubo kungenzeka ngaphandle kwabo.

ngokulinganayo

A ngokwahlukana okucacile phakathi chromosome amabii lamaseli elakhiwe phakathi ukuqoqwa, kungenteka kuphela uma chromatids abhanqiwe kinetochores yabo inamathele izingongolo ezahlukene. Bipolar iphutha chromatids libizwa amfitepicheskogo, kodwa kukhona nezinye izinketho ukuthi kuphakama ngesikhathi uya kokubili lokuphotha division. Lokhu monotepicheskoe (owodwa kinetochores enamathiselwe eyodwa isigxobo) kanye sintepicheskoe (kokubili-chromosomes kinetochore axhunyiwe nomunye pole). Lapho kinetochore merotepicheskom umuntu abanjwe izigxobo ezimbili. Uzinzile kuphela ezivamile, isibopho okuguquguqukayo okwenzeka ngenxa amandla ukungezwani kusukela pole, ezinye izindlela kunenze nisondelane akusazinzile futhi esethola, kodwa kungenzeka kubangelwa indawo kinetochore.