Spindle - ziri ... Kufotokozera, kapangidwe ndi ntchito

Spindle magawano - dongosolo zosakhalitsa anapanga pa ndondomeko ya mitosis ndi meiosis, ndi kupereka khromozomu tsankho ndi kugawikana selo. Iwo ochititsa kuti: microtubule dongosolo aumbike mwa danga pakati pa mitengo yonyamulira, mawonekedwe a spindle a. Dera centromere wa kinetochores khromozomu amagwira kwa microtubules ndi spindle. Malinga ndi iye DNA kusuntha kwa mizati.

kapangidwe

Spindle tichipeza zinthu zitatu structural: microtubules, DNA ndi kugawikana zake. Pole kugawa nyama ndi bungwe kudzera centrosome, amene ali centrioles. Pankhani ya malo opanda centrosomes (zomera, ndi oocytes a mitundu ina) spindle ali mtengo lonse ndipo anaitana atsentrosomalnym. Mu mapangidwe spindle zinakhalira ndi dongosolo lina - mapuloteni galimoto. Iwo ali ndi dynein ndi kinesin.

Spindle magawano - dongosolo ochititsa kuti. mizati onse zili centrosomes - organelles kuti ndi malo microtubule bungwe. Kapangidwe ka centrosome ndi kusiyanitsa centrioles awiri, amene atazunguliridwa ndi khamu la mapuloteni osiyana. DNA Zachepetsedwa ndi mawonekedwe a chromatids awiri aphata pamodzi pa centromere malo, yomwe ili pakati pa mitengoyo. Mu centromeres ndi kinetochores, imene inadzachitika ubwenzi wa microtubules.

mapangidwe

Popeza magawano spindle - ndi dongosolo kuti ndi udindo magawano selo, kuyambira msonkhano ake akupezeka prophase. Zomera ndi oocytes pakalibe centrosomes, pakati microtubule gulu akutumikira monga chigoba cha phata la. Microtubules ali pafupi envelopu nyukiliya ndipo itha mochedwa prophase kuonetsa, ndi kupanga "prophase spindle" - tsogolo spindle olamulira.

Chifukwa chakuti maselo nyama ya centrosome atenge mbali ya gulu la pakati, chiyambi cha mapangidwe spindle mitotic ndi zikusiyana pakati pa centrosomes awiri pa prophase. Zimenezi n'zotheka chifukwa mapuloteni galimoto dynein iwo amagwira pamwamba lakunja la pakati ndi mbali mkati mwa selo nembanemba. dynein gulu Ufumuyo Kakhungu ndi, chikugwirizana ndi microtubules astral ndi kuyamba kusuntha kutha zoipa, chifukwa muli dilution wa centrosomes pa malo osiyana khungu nembanemba.

Mapeto a msonkhano

Mapangidwe chomaliza cha spindle limapezeka pa siteji prometaphase, pambuyo mofulumira nembanemba ndi kumakhaladi pakati wathunthu, chifukwa ndiye centrosomes ndi microtubules akhoza mwayi wolankhula ndi zigawo zikuluzikulu za spindle lapansi.
Komabe, pali chapadera: ndi ikuphukira yisiti mitotic spindle mapangidwe amapezeka mkati mwa phata la.

imange mapangidwe spindle ndi kuonetsa N'zosatheka njira ziwiri: gulu la microtubules padziko DNA ndi kugwirizana awo kwa wina ndi mzake mizati Zotsutsana za magawano. Zinthu zambiri zofunika kwa mapangidwe chomaliza cha spindle, kuphatikizapo DNA ndi mapuloteni galimoto anapeza m'kati mwa phata khungu, ndipo microtubules ndipo ngati centrosomes selo nyama zopezeka cytoplasm ndi, i.e., zigawo zikuluzikulu amakhala Chrixitu. N'chifukwa chake mapangidwe spindle umatha pambuyo kutha kwa envelopu nyukiliya.

kujowina DNA

Mu mapangidwe mapuloteni mitotic spindle munthu, komanso nyumba zina zambiri, ndipo ndondomeko wakhala bwino kuphunzira maselo nyama. Pa prophase, microtubules kupanga kuzungulira centrosome stellate dongosolo lomwe diverges malangizo zozungulira. Pambuyo nyukiliya yopuma Kakhungu pansi, wamphamvu Kusakhazikika kwa microtubules anayamba mwachangu anakafika m'dera limenelo ndi kinetochores DNA akhoza atathana nawo. Mbali ina ya khromozomu yomweyo akutembenukira mizati anyamata, ndi otsala anamanga oyamba microtubules wina zake, ndi pamenepo pokha kuyamba kusuntha kwa mzati bwino. Pamene ndondomeko amaliza, ndi DNA, kale kugwirizana ndi aliyense kinetochores mzati chiyambi angagwirizanitse kwa microtubules kwa mizati anyamata, kotero kuti pa ndondomeko metaphase kuti kinetochores chikugwirizana pakati machubu khumi ndi makumi anayi. mapangidwe akutchedwa kinetochore mtengo. Pang'onopang'ono lililonse khromozomu amagwirizana ndi mzati anyamata, ndipo iwo anapanga mu gawo chapakati mbale spindle metaphase.

Yachiwiri

Pali chitsanzo china chimene spindle mwina kupangidwa magawano. N'zothekanso maselo kukhala ndi centrosome, ndi maselo amene ali kwina. Dongosololi ikukhudza Popanga madzi a gamma tubulin mphete zovuta, chifukwa muli yochepa nucleation wa microtubules padziko DNA lapansi. Machubu Ufumuyo kwa kinetochore-kuphatikiza-yotsiriza, kenako polymerization wa microtubules akuyamba, ndiko kuti, olamulidwa kukula. malekezero zoipa za "kuphatikiza" ndi kukhalabe magawano chifukwa mapuloteni galimoto mizati. Ngati mapangidwe spindle nawo awiri centrosomes, izo facilitates kugwirizana microtubules, koma ndondomeko ndi zotheka popanda iwo.

mofanana

A kulekana kwakukulu pakati pa DNA awiri maselo kwaiye pa fission, chikhonza kuchitika pokhapokha ngati chromatids wophatikizidwa kinetochores awo anagwirizana kuti mizati osiyana. Maganizo zikusiyana chromatids amatchedwa amfitepicheskogo, koma pali zinthu zina zimene mungachite uka pa nthawi ya kupita onse spindle magawano. monotepicheskoe izi (wina kinetochores Ufumuyo mtengo wina) ndi sintepicheskoe (onse DNA kinetochore ogwirizana ndi ndodo imodzi). Pamene merotepicheskom kinetochore munthu azunguliridwa ndi mitengo iwiri. Kodi khola yekha ochiritsira, ochititsa kuti ubwenzi umene kumachitika chifukwa mphamvu mavuto kwa mizati, njira zina kogwirizana ndi kusakhazikika ndiponso kusintha, koma mwina chifukwa malo kinetochore lapansi.