Meiosis futhi izigaba zalo. izigaba Isici meiosis. Lokuzaliswa eziphilayo. Ukufana mitosis futhi meiosis

Mayelana eziphilayo, ukuthi baphefumule, badle, sakhe kabusha, bese kwenzeka sifa yaziwa, lena umsebenzi oyizalayo. Kodwa ngenxa lokho konke okwenzekayo? Ngezithukuthuku emabhuloki ekwakha - emangqamuzaneni okuthiwa futhi baphefumule, badle, sakhe kabusha futhi bafe. Kodwa lokhu kwenzeka kanjani?

Isakhiwo cell

It sakhiwa izitini, amabhlogo noma izingodo. Futhi umzimba zingahlukaniswa zibe amayunithi aphansi - amaseli. Zonke izinhlobonhlobo zezinto eziphilayo yingoba wabo, umehluko amanga kuphela inombolo yabo kanye nohlobo. Zakhiwa imisipha, amathambo, isikhumba, izitho zangaphakathi - kangaka yabo ingafani ukumiswa kwabo. Kodwa kungakhathaliseki ukuthi imisebenzi eyenziwa oyedwa noma kwesinye isitokisi, bonke ngothi lwabo ahlelwe mayelana efanayo. Okokuqala, yimuphi "isitini" has a igobolondo futhi yamiswa ku cytoplasm nge organelles yayo. Amanye amaseli akudingeki nuclei, bebizwa prokaryotic, kodwa kunamathuba amaningi noma ukuthuthukiswa ngaphansi eziphilayo sakhiwa eukaryotic kokuba i-nucleus lapho ukwaziswa kwezakhi zofuzo lilondolozwe.

Organelles ise cytoplasm, zihlukene futhi ezithakazelisayo, abasenzela imisebenzi ebalulekile. Ngo isilwane cell reticulum endoplasmic, ribosomes, mitochondria, Golgi apharathasi, centrioles, lysosomes futhi izakhi ngamandla. Nabo beze zonke izinqubo ukuqinisekisa ukuthi ukusebenza emzimbeni.

iseli umsebenzi

Njengoba kakade kushiwo, zonke izifunzo bukhoma, uphefumula, eveza futhi lufe. Lokhu kuyiqiniso kokubili wonke umzimba, okungukuthi, abantu, izilwane, izitshalo kanye nokunye. D., Futhi amaseli. Kuyamangalisa, kodwa "isitini" ngamunye has a impilo yayo. Ngenxa organelles yayo elamukelayo kanye recycles izakhi, umoya-mpilo, kususa yonke out ngokweqile. Yena cytoplasm futhi reticulum endoplasmic enze umsebenzi ezokuthutha, mitochondria banesibopho kuhlanganise ukuphefumula, kanye nokuvikela amandla. Golgi eziyinkimbinkimbi ehilelekile ekuqongeleleni kanye okukhipha amaseli imikhiqizo imfucuza. Enye organelles zihilelekile izinqubo eziyinkimbinkimbi. Futhi esikhathini esithile cell umjikeleto wemphilo iqala ukwehlukana ke kukhona inqubo yokuzala. It kuyafaneleka ukucabangela kabanzi.

Inqubo cell division

Lokuzaliswa - omunye izigaba yentuthuko we eziphilayo. Kuyefana nasendleleni amaseli. Ngezinye isigaba esithile ngibone umjikelezo wokuphila afakiwe nase isimo lapho ziba esekulungele ukuzalela. amaseli Prokaryotic umane ihlukaniswe kabili, enwetshiwe, bese wakha umgoqo. Le nqubo ilula futhi cishe ngokugcwele isibonelo amagciwane induku emise.

Njengoba amaseli eukaryotic isimo iyinkimbinkimbi kakhulu kunalokho. Zichitha ngezindlela ezintathu ezahlukene, ngokuthi amitosis, mitosis futhi meiosis. Ngayinye yalezi izindlela has izici zayo siqu, kuba esivela uhlobo oluthile cell. amitosis It kubhekwa elula kakhulu, futhi ibizwa nangokuthi i a ukuqoqwa kanambambili ngqo. Lapho kukhona kabili molecule ye-DNA. Nokho, division lokuphotha is ayakhekanga, ukuze le ndlela kuyinto kakhulu ukonga ngenkuthalo. Amitosis ebonwe eziphilayo unicellular, kuyilapho izicubu ezinamangqamuzana amaningi asakaze ngokusebenzisa ezinye izindlela. Nokho, ngezinye izikhathi ebuka futhi lapho encishisiwe mitotic yomsebenzi, isibonelo, ezicutshini ovuthiwe.

Kwesinye isikhathi division oqondile lathola uhlobo mitosis, kodwa abanye ososayensi bakholelwa it is a indlela ehlukile. Inkambo le nqubo, ngisho amaseli ubudala akuvamile. Okulandelayo ezocatshangelwa meiosis futhi izigaba zayo, inqubo mitosis kanye lokufanako nalokwehlukile emkhatsini yalezi zindlela. Kuqhathaniswa division elula iyinkimbinkimbi kakhulu futhi eyinkimbinkimbi. Lokhu kuyiqiniso ikakhulukazi ngokuphathelene ukunciphisa division, ukuze izigaba meiosis isici kuyinto enemininingwane kakhulu.

Indima ebalulekile cell division kukhona centrioles - organelles ethize, ngokuvamile owawuba eduze eziyinkimbinkimbi Golgi. isakhiwo ngasinye siqukethe microtubules 27 eziqoqiwe ngabathathu. Sonke lesi sakhiwo has simise cylindrical. I centrioles abahileleke ngokuqondile kumiswa lokuphotha amaseli inqubo division ngokungaqondile, okuzoxoxwa olwengeziwe.

mitosis

Isikhathi iseli kuyahlukahluka. Abanye bahlala izinsukwana, kodwa ezinye akunakubangelwa isikhathi eside, ngenxa ushintsho yabo ephelele kwenzeka kakhulu kuyaqabukela. Yebo, cishe zonke lezi amaseli ukukhiqiza kabusha nge mitosis. Iningi lawo abantu phakathi nenkathi division kwaba amahora 10-24. Mitosis ngokwayo ithatha isikhathi esincane isikhathi - in the izilwane mayelana 0.5-1 ihora, kanti nezitshalo mayelana 2-3. Le ndlela yokwenza kuqinisekisa ukuthi ukukhula sabantu cell nokukhiqizwa ezifanayo zofuzo ukugcwaliswa amayunithi abo. waphawula Ngakho ngokuqhubeka izizukulwane ezingeni leliphansi. Kulokhu, inani lezakhi zofuzo ayiguquki. Le ndlela yokwenza yiyona ifomu evamile ukuveza kumaseli eukaryotic.

Inani lale uhlobo division likhulu - le nqubo kusiza ukuba sikhule futhi sikhiqize kwezicubu, lapho kukhona ukuthuthukiswa wonke umzimba. Ngaphezu kwalokho, kuyinto ngesisekelo mitosis ukukhiqizwa kabusha asexual. Futhi esinye isici - ukuhamba amaseli bese esikhundleni akusebenzi kakade. Ngakho-ke, sikholelwa ukuthi ngenxa yokuthi esigabeni meiotic nzima ke indima yayo akulungile ephakeme kakhulu. Zombili lezi zinqubo zinemisebenzi eyahlukene zibuye e ebalulekile yabo futhi Irreplaceable.

Mitosis siqukethe izigaba eziningana, zehlukene izici zabo morphological. Isimo lapho iseli lilungiselelwa division ngokungaqondile, ngokuthi interphase, futhi inqubo ngokwalo lihlukaniswe by 5 izigaba, okumele kubhekwe kabanzi.

Izigaba mitosis

Ngenkathi interphase cell silungiselela division: synthesis DNA namaprotheni. Lesi sigaba sehlukaniswe eziningana, lapho kukhona ukukhula lonke isakhiwo kanye ne-chromosome ukubuyelela kabili. Kuleli zinga, iseli ihlala kufika ku-90% wayo yonke umjikelezo wokuphila.

Labo abasele abanga-10% ithatha ngqo sigaba izigaba 5. Ngezinye mitosis zezitshalo amaseli is nazo zakhululwa Preprophase, okuyinto engekho kuzo zonke ezinye izimo. Ukwakheka izakhiwo ezintsha, umnyombo ushukumiseleka ukuba isikhungo. Kwakheka preprophase band, uphawu ehlongozwayo besigaba esizayo.

Ngamanye amaseli namanje inqubo mitosis simiswe ngalendlela lelandzelako:

Ithebula 1

Ngemva kokuphothulwa sokuhlukanisa zofuzo Imininingwane cytokinesis kwenzeka noma cytokinesis. Le nkulumo ibhekisela kumiswa izidumbu zabantu indodakazi amaseli emzimbeni kamama. Ngakho organelles ngokuvamile ahlukaniswe isigamu, nakuba kungase kube okuhlukile, kwakheka ukwahlukanisa is. Cytokinesis is aziqabukeli ngo lwesigaba ahlukene, njengoba umthetho, bakubheka njengobuthakathaka njengengxenye telophase.

Ngakho, ngo-izinqubo ezithakazelisayo kakhulu ezihilela-chromosomes ukuthi zinokwaziswa zofuzo. Kuyini futhi kungani sibaluleke kangaka?

mayelana Ama-chromosomes e

Ngisho ngaphandle kokuba nakancane izici zofuzo, abantu base bazi ukuthi eziningi izinga inzalo axhomeke abazali babo. With ukuthuthukiswa biology, kwaba sobala ukuthi kule noma lolo lwazi umzimba lilondolozwe engqamuzaneni ngalinye, futhi ingxenye yalo kudluliselwa izizukulwane ezizayo.

Ekupheleni kwekhulu le-19 kwaba-chromosomes wathola - izakhiwo ehlanganisa eside molecule e-DNA. Lokhu kwenza kwaba nokwenzeka nge ngcono nangezibonakhulu, ngisho manje ongazibona ngesikhathi division kuphela. Ngokuvamile udumo kokutholakala usosayensi German V Fleming, owathola hhayi kuphela ukuhlela konke okuye kwafundwa phambi kwakhe, kodwa futhi nomthelela; yena waba ngomunye wabokuqala ukuphenya isakhiwo yeselula, meiosis futhi izigaba zayo, kanye owaqamba igama elithi "mitosis". lo mqondo "chromosome" kwahlongozwa kamuva nabanye ososayensi - a histologist German G. Heinrich Wilhelm Gottfried von Waldeyer-Hartz.

chromosome isakhiwo ngesikhathi lapho kuyabonakala, ulula - Zingamashumi chromatids ezimbili sihlanganyela nabo phakathi centromere. Kuyinto ukulandelana ezithile nucleotide futhi edlala indima ebalulekile kuseli ayanda. Ekugcineni chromosome ubheka prophase futhi metaphase, lapho kungase kube ngcono ukubona, ke ungathi H. incwadi

Ngo-1900 kwatholakala imithetho Mendel sika, echaza izimiso ukudluliswa zezici sitholwa njengefa. Khona-ke kwaba sobala ukuthi chromosome - lena okuthile ukwaziswa kwezakhi zofuzo udluliselwa. Esikhathini esizayo, ososayensi olwenziwa uchungechunge ucwaningo afakazela lokho. Bese waba isihloko cwaningo kanye nomthelela kubo has a division buyout cell.

meiosis

Ngokungafani lokhu mitosis indlela ekugcineni kuholela ekwakhekeni lamaseli ezimbili iqoqo Ama-chromosomes e izikhathi 2 lincane yasekuqaleni. Ngakho inqubo meiosis kuyinto ushintsho isigaba kusuka diploid ukuba haploid, lapho kuqala sikhuluma ukuqoqwa kwemibhalo, futhi okwesibili - yonke cell. Ukubuyisela isethi egcwele Ama-chromosomes e kwenzeka ngokusebenzisa Fusion obengeziwe gametes. Ngenxa ukwehla inani lezakhi zofuzo, le ndlela namanje kuchazwa njengendlela division ukunciphisa-cell.

Meiosis futhi izigaba zalo wafunda ezifana ososayensi adumile njengoba V. Fleming, E. Strasburgrer VI Belyaev nabanye. Lolu cwaningo yale nqubo kumaseli kokubili izitshalo nezilwane, usaqhubeka - ngakho-ke nzima. Ekuqaleni, le nqubo kubhekwa okuhlukile mitosis, Nokho, cishe ngokushesha nje ngemva ukuvulwa esafuna ahlukanisa njengento esetshenziswayo ehlukile. Izimpawu meiosis nokubaluleka kwalo theory aqalwa ngokwanele echazwe Awugustu Wiseman ngo-1887. Kusukela ngaleso sikhathi, isifundo yenqubo meiosis wathuthuka kakhulu, kodwa okutholakele angakafakwa ngawo atholakala engenabufakazi.

Meiosis akufanele kudidaniswe umugqa lwegciwane, nakuba bobabili izinqubo ahlobene eduze. Ngo ukwakheka kwamaseli ubulili, kokubili izindlela behileleka, kodwa kukhona abanye umehluko omkhulu phakathi kwabo. Meiosis kwenzeka ngezinyathelo ezimbili sokuhlukanisa ngamunye esakhiwa ngezigaba ezine eziyinhloko, abe sekhefu elifushane phakathi kwazo. Isikhathi lonke inqubo incike inani DNA nucleus futhi ohlakeni lwale nhlangano chromosomal. Ngokuvamile, kuba eside kakhulu uma kuqhathaniswa mitosis.

Phela, enye yezimbangela ezinkulu zinhlobo abalulekile ukwehluka - ukuthi meiosis. Setha wama-chromosomes ngenxa ukuncishiswa division ihlukaniswe yaba izingxenye ezimbili, ukuze kukhona inhlanganisela ezintsha zofuzo, ikakhulukazi engase ukwandisa nezimo kanye nezimo eziphawula izinto eziphilayo, ngenxa kokuthola ezithile izimfanelo kanye izimfanelo.

Izigaba meiosis

Njengoba sekushiwo, yilelo nalelo libe nesigaba ukunciphisa-kweselula evamile yahlukaniswa ngezigaba ezimbili. Ngayinye yalezi izigaba lihlukaniswe by 4. Futhi ngisho isigaba sokuqala meiosis - prophase mina, esikhundleni salokho, selihlukene laba 5 izigaba ehlukile. Njengoba lolu cwaningo yale nqubo iyaqhubeka, kungaba angahlangani nabantu futhi kwabanye esikhathini esizayo. Manje ukuhlukanisa izigaba ezilandelayo meiosis:

Ithebula lesi-2

Ngakho-ke, kusobala ukuthi izigaba zokuhlukaniswa kwe-meiosis ziyinkimbinkimbi kakhulu kunezinqubo ze-mitosis. Kodwa, njengoba sekushiwo kakade, lokhu akukuvimbeli indima yezinto eziphilayo ngokuhlukana okungaqondile, ngoba benza imisebenzi ehlukene.

Ngendlela, i-meiosis nezigaba zayo ziphinde zihlonishwe kwezinye ze-protozoa. Nokho, njengomthetho, kufaka hlangana ukuhlukana okulodwa. Kucatshangwa ukuthi le fomu eyodwa-esiteji kamuva yaba yifomu lesimanje, lesibili.

Ukungafani nokufana kwe-mitosis ne-meiosis

Ekuboneni kokuqala kubonakala sengathi umehluko phakathi kwalezi zinqubo ezimbili kubonakala, ngoba lezi ziindlela ezihluke ngokuphelele. Kodwa-ke, ngokuhlaziywa okujulile, kuvela ukuthi umehluko phakathi kwe-mitosis ne-meiosis akuyona yonke indawo, ekugcineni iholela ekwakheni amangqamuzana amasha.

Okokuqala, kubalulekile ukukhuluma ngalokho lezi zinto ezifanayo. Eqinisweni, kunezivumelwano ezimbili kuphela: ngokulandelana kwezigaba ezifanayo, futhi naseqinisweni lokuthi Ngaphambi kokubili izinhlobo ze-fission, ukuphindaphinda kwe-DNA kwenzeka. Nakuba, ngokuphathelene ne-meiosis, ngaphambi kokuqaliswa kwe-prophase mina le nqubo ayigcwalisi ngokuphelele, iphela kwesinye sezigaba zokuqala. Ukulandelana kwezigaba, noma kunjalo, kodwa, empeleni, izenzakalo ezenzeka kuzo azihambisani ngokuphelele. Ngakho ukufana phakathi kwe-mitosis ne-meiosis akulona okuningi.

Ukungezwani kukhulu kakhulu. Okokuqala, i-mitosis ivela kumaseli angama-somatic, kuyilapho i-meiosis isondelene kakhulu nokubunjwa kwamaseli wesondo no-sporogenesis. Ezizigaba ngokwazo, izinqubo azihambisani ngokuphelele. Isibonelo, ukudlula kuma-mitosis kwenzeka ngesikhathi se-interphase, futhi lokho akunjalo ngaso sonke isikhathi. Esikhathini sesibili, i-anaphase ye-meiosis yenzeka kule nqubo. Ukunciphisa izakhi zofuzo ngokuhlukana okungaqondakali ngokuvamile akukwenziwa, okusho ukuthi akuthinti indima ekuthuthukiseni ukuguquguquka kwemvelo nokugcinwa kwezinhlobonhlobo ze-intraspecific. Inombolo yamaseli aphethwe yi-mitosis yimibili, futhi izakhi zofuzo zifana namangqamuzana omama futhi zinesethi se-diploid yama-chromosomes. Ngesikhathi sokuhlukaniswa, konke kuhlukile. Umphumela we-meiosis ngamaseli angama-haploid angu- 4 , ahluke esitokisini somama. Ngaphezu kwalokho, lezi zici zombili zihluka kakhulu ngesikhathi eside, futhi lokhu akufanele nje kuphela umahluko phakathi kwenani lezinyathelo zokuhlukaniswa, kodwa futhi nobude besigaba ngasinye. Isibonelo, i-meiosis yokuqala prophase ihlala isikhathi eside, ngoba ngalesi sikhathi, ukuhlanganiswa kwe-chromosome nokuwela phambili kwenzeka. Yingakho ihlukaniswa ngezigaba eziningana.

Ngokuvamile, ukufana phakathi kwe-mitosis ne-meiosis akuyona into ebalulekile uma kuqhathaniswa nokuhlukana komunye nomunye. Kungenakwenzeka ukuphazamisa lezi zinqubo. Ngakho-ke, manje kuyamangala nakakhulu ukuthi ukwehlukaniswa kwehlisela kwakubhekwa njengama-mitosis.

Imiphumela ye-meiosis

Njengoba sekushiwo kakade, emva kwenqubo yokuhlukaniswa kwehliswa, kunokuba iseli lomama elinesethi ye-diploid ye-chromosomes, ama-haploid amane akhiwa. Futhi uma sikhuluma ngokungafani phakathi kwe-mitosis ne-meiosis - lokhu kubaluleke kakhulu. Ukubuyiselwa kwemali edingekayo, uma kuziwa emangqamuzaneni obulili, kwenzeka emva kokukhulelwa. Ngakho-ke, ngesizukulwane ngasinye esisha, inani lama-chromosomes aliphindaphindi kabili.

Ngaphezu kwalokho, phakathi ne-meiosis, ukutholakala kabusha kwezakhi zofuzo kwenzeka. Esikhathini sokukhiqiza lokhu kuholela ekusungulweni kwezinhlobonhlobo ze-intraspecific. Ngakho iqiniso lokuthi ngisho nezingane zakini zihluke kakhulu komunye nomunye kungumphumela we-meiosis.

Ngendlela, ubuhlanya bezinye izinhlobo zemfuyo embusweni wezilwane nakho kuyinkinga yokuhlukaniswa. Iphuzu liwukuthi ama-chromosomes yabazali abangezinhlobo ezihlukahlukene angeke angene ekuhlanganiseni, okusho ukuthi ukwakheka kwamaseli e-sexable asebenzayo akunakwenzeka. Ngakho-ke, yi-meiosis ehambisana nokuthuthukiswa kwemvelo kwezilwane, izitshalo nezinye izinto eziphilayo.