Cell division

Lesi sigaba akuyona nje yokuvula ubuqotho kwezicubu, kodwa ukukhiqizwa eziphilayo. Ngokwaso cell division kuhilela ukwakheka kwamaseli ezimbili noma ngaphezulu indodakazi kusukela ongayedwa. Ngokuvamile ama-chromosome ibekwe ezindaweni ezibalulekile kakhulu inqubo cell division. Is they banesibopho ukudluliswa kolwazi phakathi izizukulwane.

Cell division. Mitosis futhi Meiosis

Kukhona izinhlobonhlobo emibili eyinhloko division - mitosis futhi meiosis. Eyokuqala ihilela kumiswa olulodwa sabazali iseli ezimbili ingane. Inani lezakhi zofuzo emangqamuzaneni ezimbili uhlala iyafana kuseli umzali, amaseli ie ziyafana. Ukwandisa inani lezakhi zofuzo kwenzeka ngaphambi division. Ngakho, iseli uguqulwa kusukela diploid ukuze tetraploid. Ekupheleni amaseli ezimbili diploid akhiwa.

Meiosis ibizwa ngokuthi ukwakheka kwamaseli ezine. Kulokhu, ngasinye salezi-chromosomes e isigamu kunalawo umzali. Meiosis ngokuvamile kwenzeka ngokushesha ngemva kokuba division lokuqala. Ngenxa yalokho we diploid olulodwa etholwe ezine haploid.

Phakathi cell division kumele akhule, silungiselela division entsha. Phakathi nalesi sikhathi, ke aqoqana eziningi amaprotheni futhi kabili organelles ezibaluleke kakhulu, futhi nabo, futhi kuma-chromosome.

Ukuhlukanisa ezine izigaba mitosis, okuyinto ukulandela nomunye futhi wandise kufika emahoreni amabili. Mitotic cell division kusikisela izinyathelo ezilandelayo.

Ngo esigabeni sokuqala ukunweba centrioles izinti iseli. Ngemva kwalokho, ukwakheka uthi lokuphotha. Ngokuvamile ama-chromosome kuzobonakala ngaphezulu. Ngesikhathi esifanayo ancibilikisa ulwelwesi zenuzi, le nucleolus bese inyamalala.

Isigaba sesigaba sesibili siwukuthi chromosome kufanele uhlale eduze nenkabazwe esitokisini futhi babiza division uthi lokuphotha.

In the isinyathelo sesithathu indodakazi-chromosomes noma chromatids ziqale inqubo kwehlukana ngenxa izinti amaseli nokwakha uthi lokuphotha.

In the isinyathelo esilandelayo zinyamalale lokuphotha, emhlabeni-chromosomes kakade bahlakazeka izinhlamvu ziqala ukwakheka imvilophu zenuzi. Ngemva kwalokho uhlukanisa cytoplasm nendodakazi amaseli akhiwa. Kusukela cell division kwenzeka.

meiosis

Meiosis uvame elihlobene ne ukuzala amangqamuzana kanye kumiswa amaseli ucansi isikhunta, ezitshalweni nasezilwaneni. Cell division yakhiwa izinqubo ezimbili ezilandelanayo division, Nokho-chromosome kabili kwenzeka nje ngaphambi division lokuqala. Yingakho amaseli okuholela aqukethe ingxenye inani lezakhi zofuzo. Inqubo meiosis yakhiwa izigaba ezimbili eziyinhloko - ngaphambi ukuhlukana futhi sokuhlukanisa up, ngasinye sazo yahlukaniswa ngezigaba ehlukile.

In the isinyathelo kuqala ngaphambi sokuhlukanisa-chromosomes kukhona sasivumela ebonakalayo kahle. Ngakho homologous chromosome pair izinhlamvu ziqala ukwakheka, uvalwe ukunamathela nomunye, bese ezimazombe kanye ubude balo lonke. Ngemva kwalokho, izifunda homologous ka-chromosome bashintshisane izingxenye phakathi nomunye futhi zihlukaniswa. Ngaphezu kwalokho Ama-chromosomes e homologous kumelwe iyahambelana kanye yenkabazwe. Ngesikhathi sigaba esilandelayo-chromosome, okuyinto aqukethe chromatids ezimbili ziqale washintsha maqondana izingongolo. I iphutha of pair ngamunye izimele nezinye ngazimbili wama-chromosomes kwehlukana. kwakhiwa Ngakho indodakazi amaseli nge uhhafu inani lezakhi zofuzo.

Eyesibili cell division. Isinyathelo sokuqala sihilela ukubhujiswa imvilophu enuzi kanye ukunyamalala nucleoli. Ngemva kwalokho bavele uthi lokuphotha. Khona-ke, kuma-chromosome kumelwe iyahambelana enkabazwe by anamathisela uthi lokuphotha. In esigabeni sesithathu kokubili chromatids indodakazi amaseli kancane kancane washintsha ukuze izingongolo. Ngemva kwalokho kukhona amaseli neqoqo elilodwa chromosome. Ngaphezu kwalokho ama-germ cells akhiwa. inani lezakhi zofuzo engqamuzaneni entsha kubuyiselwa emva nokuhlanganiswa gametes.