Ukwahlukana kwesahluko ... Inkcazo, isakhiwo kunye nemisebenzi

Ukugxotha kwe-fission yindlela yokwakheka kwexesha okwakhiwa ngexesha leenkqubo ze-mitosis kunye ne-meiosis, kwaye inikeza ukwahlukana kwe-chromosome kunye nokwahlukana kweseli. I-bipolar: inkqubo ye-microtubule, eyenziwe kwithuba phakathi kwezibonda, ifana nesigxina esimo. Kwimimandla ye-centromere, i-microtubules ye-spindle ifakwe kwi-chromosome kinetochores. Ngokutsho kwabo, i-chromosomes iya kwiipalo.

Ulwakhiwo

I-spindle ye-fission iqulethe izinto ezintathu ezisisiseko: i-microtubules, iiplisi ze-fission kunye nama-chromosomes. Izibonda zokuhlula kwizilwanyana ziququzelelwe ngoncedo lwe centrosomes, apho i-centriol iqulethwe khona. Ngokungabikho kwe-centrosomes (kwizityalo, nakwi-oocytes kwezinye iintlobo zezilwanyana), i-spindle ineepalo ezibanzi kwaye ibizwa ngokuba yi-centrosome. Ngokwakheka kwe-spindle, esinye isakhiwo sithatha inxaxheba, iiprotheni ze-motor. Bayizo ze-dynes kunye neentlanzi.

Ukuthungulwa kwesahluko kuyisakhiwo se-bipolar. Kuzo zombini iipalini ziyi-centrosomes - i-organelles, ezo ziziko lokubambisa ii-microtubules. Ngokwakheko lwe-centrosome, i-centrioles eyaziwayo, ijikelezwe ngamaprotheni amaninzi ahlukeneyo. Ama-chromosomes avunyelwe, anefom yee-chromatids eziqhotyoshelweyo kwisayithi le-centromere, ziphakathi kwezibonda. Kwimimandla ye-centromere, kukho i-kinetochores apho i-microtubules ifakela khona.

Uqeqesho

Ekubeni i-fission spindle yindlela ejongene nokuhlukana kweseli, ukuqala kwendibano yayo kubakho kwiprophase. Kwizityalo nakwi-oocytes, ngokungabikho kwe-centrosome, isikhungo semibutho ye-microtubules yinqabileyo yengundoqo. I-microtubules isebenzisa imvulophu yenukliya kwaye ekupheleni kwenkqubo yokuqhelanisa ukuphela kwayo iphela kwaye "i-prophase spindle" yenziwa - i-axis ye-future spindle yecandelo.

Ngokombono wokuthi kwiiseli zezilwanyana yi-centrosome ekhonza njengeziko lemibutho, ukuqala kohlobo lwe-fission yokwakhiwa kwe-spindle ukuphambana kwama-centrosomes phakathi kwexesha leprophase. Oku kunokwenzeka ngenxa yeeprotheni dyneins: zifakela kummandla wangaphandle we-nucleus, kunye nomgca wangaphakathi lwesibane. Iqela le-dynes eliqhotyoshelweyo kwi-membrane lidibanisa ne-astral microtubules kwaye baqala ukunyuka ukuya ekupheleni, ngenxa yoko i-centrosomes ihlanjululwa kunye namacandelo ahlukeneyo embranini yeseli.

Ukugqiba ibandla

Ukuqulunqwa kokugqibela kwe-fission spindle kwenzeka kwinqanaba le-prometaphase, emva kokunyamalala kwebhubhane le nyukliya kuya kugcwala, emva koko, emva koko, i-centrosomes kunye ne-microtubules zinokufikelela kwiinkalo ze-spindle.
Nangona kunjalo, kukho enye ihlukile: kwimvubelo ehlumayo, ukubunjwa kwe-fission spindle kwenzeka ngaphakathi kwisucleus.

Ukubunjwa kwamacwecwe okugxotha amafayili kunye nokuqhelaniswa kwazo akunakwenzeka ngaphandle kweenkqubo ezimbini: umbutho wee-microtubules ezijikeleze i-chromosomes kunye nokuzihlanganisa omnye komnye kwiipalini ezichaseneyo. Izinto ezininzi ezifunekayo ukwenzela ukubunjwa kokugqibela kwe-fission spindle, kubandakanywa nama-chromosomes kunye nama-protein, zifumaneka ngaphakathi kwe-cell nucleus, kunye ne-microtubules kwaye, ukuba isilwanyana sezilwanyana, i-centrosomes ziqulethwe kwi-cytoplasm, oko kukuthi, iinqununu zodwa zihlukana. Yingakho ukubunjwa kwe-spindle kuphela kuphela emva kokusabalalisa kweemvulophu yenukliya.

Ukulungelelaniswa kwama-chromosomes

Ukubunjwa kwe-spission ye-fission kubandakanye iiprotheni, kunye nezinye izakhiwo, kunye neeseli zezilwanyana le nkqubo ifundwe kakuhle. Ngexesha leprophase, i-microtubules yakha isakhiwo esifane neenkwenkwezi malunga ne-centrosome, edibanisa i-radially. Emva kokuba i-membrane ye-nucleus idibene, i-microtubules ezinamandla ezinokuthi zenzeke ziqala ukucubungula le ndawo kwaye i-kinetochores ye-chromosomes iyakwazi ukuzifumana. Ezinye ze-chromosomes zivele zivele kwiipalati eziphambene, ngelixa abanye beqala ukudibanisa ne-microtubules enye yezibonda, kwaye ke kuphela baqale ukuya kwi-pole efunwayo. Xa inkqubo igqityiwe, i-chromosomes esele idibene nayo nayiphi na ipolisi iyaqhotyoshelwa yi-kinetochores kwii-microtubules ukusuka kwipolisi echaseneyo, ngaloo ndlela, ngexesha le-metaphase, inkqubo ye-metaphase, iishumi ezimashumi mane ukuya kumashumi amathathu zixhomekeke kwi-kinetochores. Olu lwakhiwo lubizwa ngokuba yi-kinetochore bundle. Kancinci, nganye i-chromosomes idibene nesigxina esichaseneyo, kwaye yakha iplati ye-metaphase kwindawo engundoqo ye-spindle yecandelo.

Inketho yesibini

Kukho omnye umzekelo, ngokubhekiselele kulowo udidi lwesahlulo lunokukwenza. Oku kunokwenzeka kwiiseli ezine centrosome, kunye neeseli ezingabikho kuzo. Iindandatho ze-gamma-tubulin zincinci kwinkqubo, ngenxa yokuba kukho i-nucleation yama-microtubules amfutshane malunga nama-chromosomes. Ii-tubes zijoyina i-kinetochores kunye ne-end-end-end, emva koko i-polymerization ye-microtubules iqala, oko kukuthi, ukukhula okulawulwayo. I-minus iphela idibanise "udibanise" kwaye uhlale kwizibonda ngenxa yeeprotheni zeenjini. Ukuba iqela le-centrosomes lithatha inxaxheba ekubunjweni kwe-fission spindle, oku kuququzelela ukuxhamla kwe-microtubules, kodwa inkqubo inokwenzeka ngaphandle kwabo.

Ngokulinganayo

Ukwahlula ngokucacileyo kwama-chromosomes phakathi kweeseli ezimbini ezenziwa ngexesha lokwahlukana kunokukwenzeka kuphela ukuba i-chromatids yomibini kunye ne-kinetochores idibene nezibonda ezahlukeneyo. Ukungafani kwe-bipolar ye-chromatids kuthiwa yi-amphithecic, kodwa kukho ezinye iindidi eziphakanyiswayo ngelixa i-fission spindle iqokelelwa. I-monotepic (enye i-kinetochore idibanisa ipolisi enye) kwaye i-synthetic (zombini i-chromosome ifakwe kwi-pole enye). Xa i-merotepic one kinetochore ithathwa ngokukhawuleza ngeebonda ezimbini. Kuphela ukubophezela kwe-bipolar okubangelwa yimibutho yokuxhatshaza kwiipalo, kuzinzileyo, iindlela zokuhlala ezizinzileyo zizinzileyo kwaye ziguqulwa, kodwa zinokwenzeka ngenxa yendawo ye-kinetochore.