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Sex Determination and Sex-Linked Traits. Chapter 4. Outline. Sex Determination Different Karyotypes sry gene and maleness Sex Linked Traits Barr Bodies. 1. Chromosomal Sex determination Systems. XX-XO XX-XY ZZ-ZW Haplodiploidy.
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Sex Determination and Sex-Linked Traits Chapter 4
Outline • Sex Determination • Different Karyotypes • sry gene and maleness • Sex Linked Traits • Barr Bodies
1. Chromosomal Sex determination Systems XX-XO XX-XY ZZ-ZW Haplodiploidy
2. Genetic Sex Determining Systems • Genic Balance Sex Determination • Environmental Sex Determination drosophila Slipper limpet
Drosophila: genic balance * autosome= any non-sex chromosome
Human Karyotypes Klinefelter Syndrome Non-disjunction NORMAL Turner Syndrome
Maleness • Determination of maleness is due to sry gene of Y chromosome • Expression of gender is more complex than just sry gene. • Example: androgen insensitivity • Xy genotype • Many female characteristics!
Sex Linked (X-linked) Traits (3 examples) • Human Color Blindness
Sex Linked (X-linked) Traits • White eye Drosophila
Hemophilia Pedigree of hemophilia XhY x XHXh ½ XH ½ Xh ¼ XHXh ¼ XhXh ½ Xh ½ Y ¼ XHY ¼ XhY
Barr Bodies & X-Inactivation • What are they? • Why does it occur?
X-Inactivation in cats Tortoiseshell Color
Y-Linked Inheritance • Few genes on Y chromosomes • Few examples of known Y linked traits to date