2-mavzu: odam irsiyatining moddiy asoslari

Meyozning mitozdan farqi; 1) mitoz bir marta, meyoz ikki marta bo‘linishdan iborat.
2) Mitozda ona hujayraning diploid to‘plamli xromosomalari saqlangan holda qiz hujayralarga beriladi. Meyozning qiz hujayralari – gametalarida xromosomalarning gaploid to‘plami bo‘ladi.
3) Mitoz bo‘linishda ikkita qiz hujayra, meyoz bo‘linishda esa 4 ta gameta hosil bo‘ladi.
4) Mitozning anafazasida ikki qutbga xromosomalar yakka-yakka holatda tarqaladi. Meyozning reduksion bo‘linishini anafazasida xromosomalar sentromeri alohida-alohida bo‘lmagani sababli ikki qutubga juft-juft holatda tarqaladilar.
5) Meyozning reduksion bo‘linishi profazasi uzoq muddatli bo‘lib, ota-ona juft xromosomalari o‘rtasida konyugatsiya hodisasi ro‘y beradi, mitozning profazasida bunday hodisa kuzatilmaydi.
Meyoz bo’linishning biologik ahamiyati
Meyoz bo’linish natijasida xromosomalar sonining kamayishi kuzatiladi. Agar meyoz bo’linish davomida xromosomalar soni kamaymaganda edi, har bir yangi avlodda urug’lanish tufayli xromosomalar soni tinmasdan ikki hissadan ortib boraverardi.
Meyoz bo’linish va gametalar hosil bo’lishi mobaynida xromosomalarning turli xil kombinatsiyalari hosil bo’lib, ota-ona xromosomalari aralashgan holda bo’ladi. Bundan tashqari gomologik xromosomalarning konyugatsiyasi, ya’ni o’xshash qismlari bilan ayirboshlanishi (krossingover) tufayli ham xromosomalarda irsiy axborotning yangi to’plami paydo bo’ladi. Ota–ona xromosomalarini kombinatsiyalashuvi va ular orasidagi krossingover natijasida yangi tarkibli xromosomalarni hosil bo’lishi organizmlarda irsiy o’zgaruvchanlikni keltirib chiqaradi. Irsiy o’zgaruvchanlik organizmlar evolyutsiyasiga olib keluvchi asosiy omillardan biri sanaladi. Ayrim holatlarda meyoz jarayonida xromosomalarning gametalarga tarqalishi teng bo’lmasligi, 1-2 xromosoma normadan ortiqcha, ikkinchisida esa 1-2 xromosoma kam tarqalishi mumkin. Ular monosomik va nullisomik. Bunday holat organizm rivojlanishining buzilishiga, xususan, odamlarda turli kasalliklarning kelib chiqishiga olib keladi.

1^Tara Rodden Robinson Assistant Professor (Research), Oregon State University “Genetics For Dummies” Copyright © 2005 by Wiley Publishing, Inc., Indianapolis, Indiana.46-bet.

2^Tara Rodden RobinsonAssistant Professor (Research), Oregon State University “Genetics For Dummies” Copyright © 2005 by Wiley Publishing, Inc., Indianapolis, Indiana.48-bet.

3^Tara Rodden Robinson Assistant Professor (Research), Oregon State University “Genetics For Dummies” Copyright © 2005 by Wiley Publishing, Inc., Indianapolis, Indiana.48-bet.

4^Tara Rodden Robinson Assistant Professor (Research), Oregon State University “Genetics For Dummies” Copyright © 2005 by Wiley Publishing, Inc., Indianapolis, Indiana.(mazmun va mohiyatidan foydalanildi).

5^Fayzullaev S.S., G`ofurov A.T., Matchonov B.E. “Odam genetikasi” Toshkent ., “Ijod dunyosi”, 2003y .(mazmun va mohiyatidan foydalanildi).

6^Tara Rodden Robinson Assistant Professor (Research), Oregon State University “Genetics For Dummies” Copyright © 2005 by Wiley Publishing, Inc., Indianapolis, Indiana. 44-bet

7^Tara Rodden Robinson Assistant Professor (Research), Oregon State University “Genetics For Dummies” Copyright © 2005 by Wiley Publishing, Inc., Indianapolis, Indiana.(mazmun va mohiyatidan foydalanilgan)

8^Fayzullaev S.S., G`ofurov A.T., Matchonov B.E. “Odam genetikasi” Toshkent ., “Ijod dunyosi”, 2003y

9^Fayzullaev S.S., G`ofurov A.T., Matchonov B.E. “Odam genetikasi” Toshkent ., “Ijod dunyosi”, 2003y

10^Tara Rodden Robinson Assistant Professor (Research), Oregon State University “Genetics For Dummies” Copyright © 2005 by Wiley Publishing, Inc., Indianapolis, Indiana.107-bet

11^Tara Rodden Robinson Assistant Professor (Research), Oregon State University “Genetics For Dummies” Copyright © 2005 by Wiley Publishing, Inc., Indianapolis, Indiana.54-bet.

12^G’ofurovA.T., FayzullaevS.S. “Genetika”T. 2010 y (mazmun mohiyatidan foydalanildi)

13^Fayzullaev S.S., G`ofurov A.T., Matchonov B.E. “Odam genetikasi” Toshkent ., “Ijod dunyosi”, 2003 y (mazmun mohiyatidan foydalanildi)

14^Fayzullaev S.S., G`ofurov A.T., Matchonov B.E. “Odam genetikasi” Toshkent ., “Ijod dunyosi”, 2003 y.(mazmun mohiyatidan foydalanildi)

15^Tara Rodden Robinson Assistant Professor (Research), Oregon State University “Genetics For Dummies” Copyright © 2005 by Wiley Publishing, Inc., Indianapolis, Indiana.118-bet.

16^G’ofurovA.T., FayzullaevS.S. “Genetika”T. 2010 y. (mazmun va mohiyatidan foydalanildi)

17^G’ofurovA.T., FayzullaevS.S. “Genetika”T. 2010 y. (mazmun va mohiyatidan foydalanildi)