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2014

CHROMOSOMAL SEX DETERMINATION. Výukový materiál MB 02 - 49 Tvůrce: Mgr. Šárka Vopěnková Tvůrce anglické verze: ThMgr. Ing. Jiří Foller Projekt: S anglickým jazykem do dalších předmětů Registrační číslo: CZ.1.07/1.1.36/03.0005 Tento projekt je spolufinancován ESF a SR ČR. 2014.

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2014

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  1. CHROMOSOMAL SEX DETERMINATION Výukový materiál MB 02 - 49 Tvůrce: Mgr. Šárka Vopěnková Tvůrce anglické verze: ThMgr. Ing. Jiří Foller Projekt: S anglickým jazykem do dalších předmětů Registrační číslo: CZ.1.07/1.1.36/03.0005 Tento projekt je spolufinancován ESF a SR ČR 2014

  2. in use by gonochorists • they have one sex chromosome = heterochromosome (gonosome) • the other chromosomes are called autosomes • one sex chromosome is geminate • according to the sex there exist either: • in a non-homologic pair with a non-geminate chromosome • or as a pair of homologic chromosomes CHROMOSOMAL SEX DETERMINATION

  3. CHROMOSOMAL SEX DETERMINATION • the geminate heterochromosome is marked X- chromosome • non-geminate heterochromosome (so called allosome) is marked Y-chromosome

  4. by mammals and by humans is present: • by females a couple of homologic chromosomes XX • by males non-geminate chromosomal couple XY • females produce only eggs • eggs contain chromosome X = homogametic sex CHROMOSOMAL SEX DETERMINATION

  5. males produce one half of sperms with chromosome X • one half of sperms with chromosome Y = heterogametic sex CHROMOSOMAL SEX DETERMINATION

  6. CHROMOSOMAL SEX DETERMINATION • after the fertilization of the egg by the sperm with chromosome X => male zygote • after the fertilization of the egg by the sperm with chromosome Y => female zygote

  7. CHROMOSOMAL SEX DETERMINATION • this type of chromosomal sex determination also occurs by dioecious plants, insects except for butterflies • it is named male type or type Drosophila

  8. By birds and butterflies (and also by some fish species, amphibians and reptiles): • There is one pair of chromosomes XX in male somatic cells = males are homogametic sex Bird type: (Abraxas) homozygotic XX heterozygotic XY CHROMOSOMAL SEX DETERMINATION

  9. Non-geminate pair XY is in female cells = females are heterogametic sex • this type of chromosomal sex determination is named bird type or Abraxas type CHROMOSOMAL SEX DETERMINATION Bird type: homozygotic XX (Abraxas) heterozygotic XY

  10. heterogametic sex produces: • a half of gametes with chromosome X • a half of gametes with chromosome Y • through their fertilization necessarily develops a half of males and a half of females CHROMOSOMAL SEX DETERMINATION

  11. main evolutionary advantage: • keeping the same relation of males and females in generations • it ensures the maximum possible amount ofdescendants by gonochorists in natural populations CHROMOSOMAL SEX DETERMINATION

  12. DESCRIBE THE PICTURE

  13. DESCRIBE THE PICTURE

  14. CHALUPOVÁ-KARLOVSKÁ, Vlastimila. Obecná biologie: středoškolská učebnice : evoluce, biologie buňky, genetika : s 558 řešenými testovými otázkami. 2., opr. vyd. Olomouc: Nakladatelství Olomouc, 2010, 206 s. ISBN 978-80-7182-282-0 SOURCES

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