Dogara sanda - shi ke ... Description, sifa da aiki

Dogara sanda division - wucin gadi tsarin kafa a lokacin aiwatar da mitosis da meiosis, da kuma samar da chromosome fata da kuma cell division. Yana bipolar: microtubule tsarin kafa a sarari tsakanin sandunan, cikin siffar wani dogara sanda. A centromere yankin na chromosome kinetochores suna haɗe zuwa dogara sanda microtubules. A cewar shi da chromosomes motsa zuwa ga sandunan.

tsarin

Dogara sanda kunshi uku na asali tsarin abubuwa: microtubules, chromosomes da rabo daga sanduna. Iyakacin duniya rarraba dabbobi da ake shirya via da centrosome, wanda dauke da centrioles. A cikin hali na wurare ba tare da centrosomes (a cikin shuke-shuke, da kuma a oocytes wasu jinsunan) dogara sanda yana da fadi da iyakacin duniya da kuma kira atsentrosomalnym. A samuwar na dogara sanda da hannu ne wani tsarin - motor sunadaran. Sun kasance a cikin dynein da kinesin.

Dogara sanda division - a bipolar tsarin. Dukansu sandunan suna located centrosomes - wasu gabbansa da suke da cibiyoyi na microtubule kungiyar. A tsarin da centrosome rarrabe biyu centrioles, wanda aka kewaye da wani taron na daban-daban sunadarai. Takaice chromosomes da ciwon cikin nau'i na biyu chromatids gudanar tare a centromere site, located tsakanin sandunan. A centromeres ne kinetochores, wanda faruwa da abin da aka makala na microtubules.

samuwar

Tun da division dogara sanda - shi ne da wani tsari da cewa shi ne alhakin cell division, farko ta taron ya auku a prophase. A shuke-shuke da kuma a oocytes in babu centrosomes, microtubule shirya cibiyar hidima a matsayin harsashi na tsakiya. Microtubules ne kusa da makaman nukiliya ambulan da kuma ƙare a cikin marigayi prophase su fuskantarwa, da kuma samar da "prophase dogara sanda" - gaba dogara sanda axis.

Saboda gaskiya cewa a cikin dabba Kwayoyin ne da centrosome taka rawar da kungiyar na cibiyar, farkon samuwar mitotic dogara sanda ne hilafa tsakanin biyu centrosomes a lokacin prophase. Wannan shi ne zai yiwu saboda motor sunadaran dynein suna a haɗe zuwa da matsanancin surface da zuciyar da kuma na ciki gefen jikin tantanin. dynein kungiyar a haɗe zuwa membrane, da alaka da astral microtubules da suka fara motsawa zuwa ga mummunan karshe, saboda wanda akwai dilution na centrosomes a gaban shafukan da jikin tantanin.

A karshen taron

A karshe samuwar dogara sanda ya auku a prometaphase mataki, bayan da bacewar na membrane shi ya zama cikakken core, domin shi ne sai centrosomes da microtubules iya samun damar yin amfani da aka gyara na dogara sanda.
Duk da haka, akwai daya banda: da budding yisti mitotic dogara sanda samuwar auku a cikin tsakiya.

Thread dogara sanda samuwar kuma su fuskantarwa shi yiwuwa ba tare da biyu matakai: kungiyar na microtubules a kusa da chromosomes da su dangane da juna a gaban sandunan da division. Mutane da yawa daga cikin abubuwa wajibi ne ga karshe samuwar dogara sanda, ciki har da chromosomes da kuma mota sunadaran samu a ciki da cell tsakiya, da kuma microtubules kuma, idan dabba cell centrosomes dauke a cikin cytoplasm, Ina nufin, da aka gyara an ware daga juna. Wannan shi ne dalilin da ya sa da samuwar na dogara sanda ƙare kawai bayan da bacewar na nukiliya ambulan.

shiga chromosomes

A samuwar mitotic dogara sanda gina jiki ne da hannu, kazalika da yawa wasu Tsarin, kuma wannan tsari da aka kyau karatu a dabba Kwayoyin. A lokacin prophase, microtubules nunawa a kusa da centrosome stellate Gininsu, wanda diverges a radial shugabanci. Bayan da makaman nukiliya membrane karya saukar, tsauri rashin zaman lafiya na microtubules fara rayayye gano wannan yankin da kuma kinetochores na chromosomes za a iya gyarawa don su. Wasu ɓangare na chromosome nan da nan ya jũya a gaban sandunan, da kuma sauran farko daura to microtubules daya daga cikin dogayen sanda, da kuma kawai sai a fara motsawa zuwa ga dama iyakacin duniya. Lokacin da tsari da aka kammala, da chromosomes, riga hade da wani iyakacin duniya fara kinetochores hašawa zuwa microtubules daga m sandunan, don haka da cewa a lokacin metaphase tsari zuwa kinetochores an haɗa tsakanin goma da kuma arba'in shambura. Wannan samuwar ake kira da kinetochore masaƙa. A hankali kowane chromosome ake dangantawa da kishiyar iyakacin duniya, kuma suna kafa a tsakiyar rabo daga dogara sanda metaphase farantin.

Zabi na biyu

Akwai wani labari a cikin abin da dogara sanda za a iya kafa division. Shi ne kuma zai yiwu ga Kwayoyin da ciwon da centrosome, kuma domin Kwayoyin a cikin abin da suka kasance mãsu fakowa ba. A tsari ya shafi cikin gamma tubulin zobe hadaddun, saboda abin da akwai short nucleation na microtubules a kusa da chromosomes. Tubes a haɗe zuwa kinetochore-da-karshen, bayan da Polymerization na microtubules fara, wato, sarrafawa girma. Korau iyakar da "Ci" da kuma zama a cikin division saboda motor sunadaran zura sandunan ɗaukarsa. Idan samuwar dogara sanda da hannu biyu daga centrosomes, shi facilitates dangane da microtubules, amma tsari ne yiwu ba tare da su.

daidai

A sarari rabuwa tsakanin biyu chromosomes na sel generated a lokacin fission, za a iya kawai faru idan guda biyu chromatids su kinetochores shiga zuwa daban-daban zura sandunan ɗaukarsa. Bipolar, sãɓã wa jũnamai chromatids aka kira amfitepicheskogo, amma akwai wasu zažužžukan da cewa bayyana a lokacin zuwa biyu division dogara sanda. Wannan monotepicheskoe (daya kinetochores a haɗe zuwa daya iyakacin duniya) da kuma sintepicheskoe (duka kinetochore chromosomes suna da alaka da daya iyakacin duniya). Lokacin da merotepicheskom daya kinetochore aka kama a tarko da sandunan. Ne barga kawai na al'ada, bipolar bond cewa ya auku saboda da tashin hankali da karfi daga cikin sandunan, da sauran bonding hanyoyin su ne m, kuma reversible, amma zai iya zama saboda da wuri na kinetochore.