Iseli umjikelezo, amasosha omzimba, iseli imvilophi

Ukuba khona inkathi cell isikhathi kusukela ngosuku lasungulwa sokuhlukanisa umama iseli division ayo noma ukufa libizwa igama elithi "ingqamuzana umjikelezo". Ngo abahlukahlukene cell ubude bayo. Ngokwesibonelo, i-basal kanye hematopoietic amaseli emathunjini amancane futhi epidermis bayakwazi ukungena umjikelezo iseli ngemva njalo emahoreni 12-16, basheshe zanda e eziphilayo omdala. Dlala ukuphila ngemijikelezo amaseli zokugcina mayelana imizuzu engu-30, lapho zenzeka ngesikhathi ukuchotshozwa okusheshayo amaqanda eziphila emanzini nasezweni, echinoderms nezinye izilwane. Inani elikhulu zinhlobo kuseli isiko izimo zokuhlola, iseli umjikelezo has a sikhashana esifushane amaminithi angu-20. Ngezinye inani eyinhloko ngenkuthalo sokuhlukanisa amaseli isikhathi nenkathi phakathi mitoses ivela amahora 10 kuya 24.

Izigaba nezikhathi lomjikelezo cell. Cell umjikelezo zezilwane nezitshalo siqukethe lezinkathi ezimbili: interphase (kwenkathi amaprotheni synthesis DNA) kanye mitosis (cell division umjikelezo). Interphase kuhlanganisa nezikhathi eziningana:

1. G1 okhombisa - sokukhula, phakathi kwesikhathi lapho zamagama amaprotheni, i-RNA nezinye cell nabavoti.

2. S-isigaba - kule isikhawu kwenzeka interphase osizayo zamagama we molecule ye-DNA ye-nuclei cell kanye kabili organelles intracellular (centrioles);

3. G2-isigaba - a yinkathi kukhona belungiselela mitosis.

Ngo amaseli ayisekho ehlukana, G1 okhombisa kungenzeka ukuthi ingabi khona, kule nkathi, zingabantu lwesigaba yokuphumula (G0).

Inqubo cell division (mitosis) has izigaba ezimbili:

1. Ukuhlukaniswa kuyi-nucleus yengqamuzana - mitosis.

2. Ukuhlukaniswa cytoplasm iseli - cytokinesis.

WokuLawula cell umsebenzi. Guqula weseli umjikelezo nezikhathi kwenzeka uma uxhumana amaprotheni - cyclins futhi kinases cyclin nasekuthengeni. Amaseli G0 sengeta uyakwazi engena iluphu bedle ukukhula izici ezihlukahlukene. Epidermal, futhi izici platelet-etholakala kukhona ezinzwa ukukhula factor, basesimweni ukuxhumana njalo nge-receptor enophephela intracellular mkhosi uhlelo eholela umbhalo amaprotheni zofuzo. Ngesikhathi kinases zingase asebenzayo kuphela nokuxhumana cyclins ethize, okuqukethwe okuyinto kushintsha njalo kulo lonke umjikelezo.

Ukuphazamiseka ukulawulwa evamile lomjikelezo cell okuholela ukwakheka izimila okuqinile. Ukuze ukwakheka izimila abulalayo amaprotheni p53 unomthwalo wemfanelo: kuyasivusa amaprotheni synthesis p21, nakho kuvimbela CDK cyclin eziyinkimbinkimbi, okuyinto nakanjani kuholela cell umjikelezo ukuboshwa e G1 futhi isigaba G2. Iseli nge-DNA obonakele akangeni S. Ngesikhathi esigabeni yokwanda koshintsho okuholela ekulahlekeni noma sokulungiswa isakhi sofuzo amaprotheni p53 ingekho kanye cell umjikelezo ukuvinjelwa ukungena mitosis, futhi isishiya amaseli asabekayo, ezinye zazo bayabulawa, kanti enye ingxenye yaba okuholela ukwakheka ebulalayo izimila.

Cell aqashwe amasosha omzimba. Basabela kanjani izivikeli mzimba kunoma zamandla ashukumisayo, okuthiwa amasosha omzimba lapho amasosha omzimba akuzona isethi balwe futhi eziyinkimbinkimbi amaprotheni ekhona igazi (umphelelisi uhlelo), ngokuthi inkulumo ethi "izingadi amasosha omzimba yeselula". It is iqondiswe ikakhulukazi ngokumelene nezilwanyana ezincane ephila phagocytes nangokumelene nezilwanyana ezincane ukuthi zingena kwamanye amangqamuzana. Ikakhulukazi kuyaphumelela ukulwa namagciwane, ama-fungus, lenyama, amagciwane isimila cells. yeselula izivikeli mzimba kubaluleke kakhulu izicubu ukwenqatshwa.

Udonga cell. Olukhuni cell odongeni, ibekwe ingaphandle ulwelwesi cytoplasmic ukuthi wenza ukuphepha, imisebenzi kwesakhiwo ezokuthutha - kuba ulwelwesi cell. Nokho-ke kubizwa ngokuthi udonga cell, ke elikhona iningi amagciwane, isikhunta, izitshalo kanye archaea. Ngokuqondene izilwane, futhi abaningi kwabangcwele elula, abanayo udonga cell.