Umsebenzi wokuzala kanye ukubaluleka begazi meiosis

Umsebenzi okuzala ka umzimba Kwenziwa ngesikhathi uxhumano of gametes ezimbili (ama-germ cells) uma kwenzeka kanye nokuthuthukiswa okwalandela zygote osizayo umzimba - amaqanda avundiswa. Ngo amaseli ngokobulili sabazali isethi ezithile n-chromosome. Wabiza haploid. Zygote kuthatha iqoqo la, it is a cell diploid, okungukuthi, inombolo chromosome 2N khona: eyodwa komama kanye eyodwa zoyise. Biological meiotic division obaluleke ngokukhethekile njengoba esitokisini liqukethe yokuthi sibonga ke, iseli haploid kwakhiwa kusukela amaseli diploid.

definition

Meiosis eziphilayo ibizwa ngokuthi uhlobo mitosis; ngenxa yayo diploid amaseli ukuphathwa kwabathintwayo of nezindlala zangasese zihlukaniswe gametes 1n. Lapho ikhenela is avundiswa, kukhona Fusion gametes. Ngakho, ke uyalulama 2N chromosome isethi. Okushiwo meiosis wukuqinisekisa ekulondolozweni esingokwemvelo uhlobo ngalunye eziphilayo-chromosomes kanye nobungako esifanele-DNA.

incazelo

Meiosis - inqubo eqhubekayo. Siqukethe futhi izinhlobo ezimbili zezinkantolo sokuhlukanisa zilandelana elandelayo nomunye: meiosis mina meiosis II. Ngamunye izinqubo, esikhundleni salokho, siqukethe prophase, metaphase, anaphase, telophase. Lesi sigaba sokuqala meiosis noma meiosis mina, yenza inani lezakhi zofuzo, isb kukhona lo mkhuba okubizwa ngokuthi ukuncishiswa division. Lapho-ke buyisigaba meiosis noma meiosis II yesibili, amaseli haploid akusho ukusongela ushintsho, it is agciniwe. Le nqubo ibizwa ngokuthi division equational.

Zonke amaseli esiteji meiosis, zithwale okunye ukwaziswa ulwazi ezakhini zofuzo.

• prophase Meiotic wokuqala - esiteji okuqhubekayo Helix chromatin kanye kumiswa chromosome. Ekupheleni lesi senzo eziyinkimbinkimbi kakhulu izinhlayiya eziyisisekelo zofuzo ekhona ifomu yayo yasekuqaleni - Ama-chromosomes e 2n2.
• Metaphase iza - uyafika ileveli enkulu Helix. Izinhlayiya eziyisisekelo zofuzo namanje akukashintshi.
• Anaphase ka meiosis kuhambisana nokuncipha. Ngalinye pair of-chromosomes sabazali ophuzisa oyedwa indodakazi amaseli ayo. nesidoda okunikelwe washintsha ukubunjwa, njengoba inombolo chromosome kwaba nengxenye ukuthi: I-pole we kwengqamuzana ngalinye kunesikhungo ezidingekile 1n2 chromosome.
• Telophase - isigaba lapho obumba core, ahlukaniswe cytoplasm. Indodakazi amaseli asedaliwe, 2 futhi ngamunye chromatids ezimbili. okungukuthi setha wama-chromosomes e-haploid kubo.
• Ngaphezu kwalokho interkinesis waphawula, sekhefu elifushane phakathi esigabeni sokuqala nesesibili meiosis. Amaseli amabili indodakazi alungele ukungena isigaba sesibili meiosis, okuyinto eyenzeka ngo-mshini esifana mitosis.

Ngakho Ukubaluleka begazi meiosis ungaphakathi yokuthi ngesinyathelo yayo yesibili izakhi eziyinkimbinkimbi zakhekile amaseli haploid 4 - 1n1 chromosome. Okungukuthi, umuntu diploid umama iseli ophilisa amane - ngalinye haploid chromosome isethi. Kwelinye meiotic degree Isigaba sokuqala nesidoda okunikelwe recombines, futhi isinyathelo sesibili Kwenziwa ukunyakaza wama-chromosomes futhi chromatids ukuba izingongolo ezahlukene iseli. Lezi izimo - umthombo ukushintshashintsha futhi inhlanganisela ezahlukene intraspecific.

Imiphumela

Ngakho, lokho okushiwo begazi meiosis, omkhulu ngempela. Okokuqala, kufanele kuphawulwe njengoba main, esigabeni eyinhloko nesisekelo gametes. Meiosis kuqinisekiswa ukudluliselwa ukwaziswa kwezakhi zofuzo kusuka umzimba zenye komunye, inqobo nje uma nokuzala ngokobulili by. Meiosis kwenza intraspecific inhlanganisela zenzeka ngoba indodakazi amaseli azigcini nje kubazali kodwa nazo ziyehluka.

Ngaphezu kwalokho, ukubaluleka begazi meiosis siqukethe ekuhlinzekeni ukunciphisa inani lezakhi zofuzo okwamanje lapho kwakhiwa amaseli lwegciwane. Meiosis kuqinisekisa haploid zabo; ngaleso sikhathi kokukhulelwa le zygote diploid chromosome isakhiwo kubuyiselwa.