Ndi reduplication ya DNA chiyani? The ndondomeko ya DNA kugawanika

The DNA - ili mu dongosolo khromozomu. khromozomu uli molekyulu umodzi ongokhala m'magawo awiri. Reduplication ya DNA - ndi kulanda zambiri pambuyo kudziona kubalana ulusi kuchokera molekyulu wina ndi mzake. Ndi chibadidwe onse DNA ndi RNA. Nkhaniyi ikufotokoza za DNA kugawanika ndondomeko.

General mfundo ndi mitundu ya DNA kaphatikizidwe

Amadziwika kuti zopotoka thonje mu molekyulu ndi. Komabe, pamene ndondomeko ya DNA kugawanika akuyamba, iwo dispiralized, ndiye akulabadira, ndi pa chilichonse buku latsopano apanga. Akamaliza pali awiri tinthu kwathunthu zofanana, omwe pali kholo ndi ulusi mwana. kaphatikizidwe iyi akutchedwa theka-ndiwofatsa. DNA mamolekyulu imakhudzidwa, nthawi imene centromere limodzi, ndipo potsiriza mogwirizana kokha pamene centromere magawano ndondomeko akuyamba.

The mtundu wina wotchedwa reparative kaphatikizidwe. Iye, mosiyana ndi wina m'mbuyomu, si kugwirizana ndi gawo selo lililonse, koma kukaponya mwambo DNA kuwonongeka. Ngati inunso lonse kuyambira chikhalidwe, selo potsirizira pake amafa. Komabe, ngati kuwonongeka ndi m'deralo, ndiye inu mukhoza kuwabwezeretsa. Malinga vuto ikhalenso kapena nadzawasankhula m'magawo awiri motere DNA mwakamodzi. Izi, monga iwo ukutchedwa, unscheduled kaphatikizidwe satenga nthawi yayitali ndi sikutanthauza kwambiri mphamvu.
Koma pamene pali reduplication a DNA, ndiye anakhala ndi mphamvu zambiri, chuma, anatambasula ndi kutalika kwa maso ake.
Reduplication lagawidwa nthawi zitatu:

• chinamwali;
• elongation;
• kuthetsedwa.

Tiyeni tikambirane ndondomeko ya DNA kugawanika.

kuchinamwali

Mu DNA anthu - ndi makumi angapo mamiliyoni awiriawiri m'munsi (nyama alipo ndi zana limodzi kudza zisanu ndi zinayi). DNA reduplication akuyamba m'madera ambiri unyolo zifukwa zotsatirazi. Pa nthawi yomweyo mu RNA ndi galamafoniyo zikachitika, koma kaphatikizidwe wa DNA lili ena malo osankhidwa. Choncho, ndondomeko yoteroyo patsogolo okwanira kuchuluka kwa thunthu amasonkhana mu cytoplasm maselo kuti azithandiza jini mawu ndi ntchito ma kuti silinagawanike. Poona zimenezi, ndondomeko ayenera kutenga malo mwamsanga. Ukufalitsidwa nthawi imeneyi ikuchitika, ndi galamafoniyo si maphunziro. Kafukufuku wasonyeza kuti DNA reduplication limapezeka kamodzi mfundo zingapo zikwi - m'madera ang'onoang'ono ndi nyukiliotayidi ndondomeko yeniyeni. Likugwirizana ndi mapulotini wapadera E, womwe wagwirizana ndi michere ina ya DNA kugawanika.

The DNA mpukutu umene apanga amatchedwa replicon. Umayamba kuyambira pa chiyambi ndipo umatha pamene enzyme kumathera kugawanika. Replicon ndi yoyenda yokha, komanso amatipatsa ndondomeko yonse ya pulogalamu yake.
Dongosololi akhoza osayamba mfundo zonse mwakamodzi, penapake iwo amayamba kale, penapake - mtsogolo; Zimatenga malo amodzi kapena mbali ziwiri zosiyana. Zochitika chichitike motere pamene fano:

• kugawanika mafoloko;
• RNA phunziroli.

kugawanika foloko

mbali imeneyi kumakhala ndondomeko yomwe mu yarns ndi sakukhudzidwa ndi apanga DNA deoxyribonucleic filaments. Mapulagi motero kupanga otchedwa diso la tizilombo ta. ndondomeko ndi yoyamba angapo zochita:

• muyeretsedwe ku mogwirizana ndi histones mu nucleosome ndi - michere monga DNA kugawanika methylation, acetylation, ndi phosphorylation kubala zosiyanasiyana mankhwala kuti zotsatira mu mapuloteni kutaya akuwayang'anira zabwino kuti facilitates amasulidwe awo;
• despiralization - ndi unwinding chimene chili chofunika yomasulira zina ulusi;
• kuswa zomangira wa hydrogen pakati pa chingwe DNA;
• divergence awo mu mbali zosiyana za molekyulu ndi;
• fixation zikuchitika ntchito SSB mapuloteni.

RNA phunziroli

Kaphatikizidwe amanyamula puloteni ina yotchedwa DNA polymerase. Komabe, kuyamba wake sangatero, kotero michere ina - ndi RNA polymerase, lomwe limatchedwanso RNA primers. Iwo apanga mu chingwe yomweyi deoxyribonucleic pa mfundo za mapolojekiti. Choncho, mwambo wa RNA kaphatikizidwe wa malekezero awiri, primers awiri ndipo adachoka analekanitsidwa DNA chingwe.

elongation

Nthawiyi akuyamba ku nyukiliotayidi Kuwonjezera ndi 3 'kumapeto kwa RNA-phunziroli, omwe amanyamula kale DNA polymerase. Iwo amamangirira wachiwiri oyamba, nyukiliotayidi lachitatu, ndi zina zotero. Latsopano ulusi m'munsi olumikiza unyolo kholo mwa maunyolo a hydrogen. Akukhulupirira kuti kaphatikizidwe wa thonje ili 5 '- 3.
Kumene amapezeka mbali ya kugawanika foloko, kaphatikizidwe udzachitika mosalekeza ndipo nthawi yomweyo lengthens. Choncho, ulusi uwu umatchedwa kutsogolera kapena kutsogolera. Iye RNA phunziroli salinso anapanga.

Komabe, pa chingwe Zotsutsana za kholo la DNA nucleotides kupitiriza kulowa RNA phunziroli, ndi unyolo deoxyribonucleic ndi apanga zosiyana kuchokera kugawanika foloko. Pankhaniyi, umatchedwa mochedwa kapena zomwe zikutsalirazi.

Pa chingwe zomwe zikutsalirazi kaphatikizidwe amapezeka mu zidutswa, mmene kumalekezero gawo la kaphatikizidwe akuyamba pamalo ena pafupi ndi ntchito yomweyo RNA phunziroli. Choncho, pali awiri anachedwa unyolo mpukutu likugwirizana DNA ndi RNA. Iwo amatchedwa Okazaki zidutswa.

Kenako zonse akubwerezedwa. Ndiye spliced wina kukhota kwa helix, wa hydrogen zimaphulika kulankhulana ulusi m'mbali, zikubweretsa unyolo lengthened pa zomwe zikutsalirazi apanga zotsatirazi mpukutu RNA phunziroli, inatuluka - Okazaki mpukutu. Kenako, mu RNA anachedwa-timafupa primers anawonongedwa ndipo DNA zidutswa likugwirizana chimodzi. Choncho dera izi zikuchitika pa nthawi yomweyo:

• mapangidwe latsopano RNA phunziroli;
• kaphatikizidwe Okazaki zidutswa;
• chiwonongeko cha primers RNA;
• kukakhalanso ku dera limodzi.

kuchotsa

ndondomeko akupitiriza malinga ngati ziwiri kukakomana ndi kugawanika mphanda, kapena mmodzi wa iwo adzadza kwa mapeto a molekyulu ndi. Titamaliza, mafoloko DNA mwana chingwe likugwirizana ndi puloteni lapansi. Zikatero, ngati pulagi ndi anawamvera kutha kwa molekyulu ndi, DNA reduplication malekezero ntchito michere wapadera.

kudzudzulidwa

Mu ndondomekoyi, yofunika kwambiri akapatsidwa ulamuliro (kapena kudzudzulidwa) wa tizilombo ta. Kuika kaphatikizidwe amalandira onse amitundu inayi nucleotides, ndi kafukufuku ndi DNA polymerase Kumuyika amasankha amene akufunika.

The nyukiliotayidi anakhumba kuti athe kupanga kumangidwa wa hydrogen komanso nyukiliotayidi ofanana pa M'manja DNA timafupa. Komanso, pakati pa shuga mankwala msana ayenera zina zonse mtunda lolingana mphete atatu zapansi awiri. Ngati nyukiliotayidi Kodi ziyeneretso izi, kugwirizana sizidzachitika.
Control ikuchitika asanapatsidwe mbali dera ndi pamaso kutembenukira pa nyukiliotayidi wotsatira. Kenako, kugwirizana kwa msana saharofosfata.

mutational masiyanidwe

Limagwirira a DNA kugawanika ngakhale amaposa molondola nthawi zonse chisokonezo filaments, amene amatchedwa makamaka "masinthidwe jini." About m'munsi awiriawiri zikwi, pali kulakwitsa kumodzi kuti konvariantnaya otchedwa reduplication.

Zimachitika pa zifukwa zosiyanasiyana. Mwachitsanzo, pa woipa mkulu kapena otsika kwambiri nucleotides deamination wa cytosine, pamaso pa mutagens mu kaphatikizidwe wa onse. Nthawi zina, zolakwa akhoza kudzudzulidwa ndi njira kukonza pomuphunzitsa zina kumakhala kovuta.

Ngati zowonongeka bwanji kugona malo, kulakwitsa sadzakhala ndi mavuto aakulu pamene pali DNA kugawanika ndondomeko. Nyukiliotayidi ndondomeko ya mbewu angayambe ndi zolakwa mating. Ndiye si choncho, ndi chifukwa olakwika akhoza ngati imfa ya foni, ndi imfa ya chamoyo wonse. Tiyeneranso adzanyamula kukumbukira kuti masinthidwe jini zochokera masiyanidwe mutational, zomwe zimachititsa dziwe jini ya plasticity.

methylation

Pa nthawi ya kaphatikizidwe, kapena nthawi yomweyo pambuyo kumachitika unyolo methylation. Akukhulupirira kuti ndondomeko imeneyi n'kofunika kuti munthu kupanga DNA ndi malangizo jini galamafoniyo. Mu ndondomekoyi mabakiteriya a DNA akutumikira chitetezo chilichonse ndi kudula michere.