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Lecture notes-2/24/15
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Non Mendelian Genetics: Sex-Linked Traits Lecture Notes
Karyotype: A photograph of a cell’s chromosomes arranged in ___________ according to size
Normal Karyotype: _______________ pairs of chromosomes
Sex-Linked Traits:
Those traits whose genes are found on the X chromosome but ________ on the Y chromosome
Examples of Sex-linked Traits:
Red-green colorblindness Male Pattern Baldness Hemophilia (Queen Victoria was a carrier) Duchene Muscular Dystrophy (fatal)
Sex-Linked Traits
Gene is attached to the X chromosome only, not found on the Y chromosome at all. Women have XX, men have XY chromosomes These disorders are more common in boys examples: red-green colorblindness
Sex-Linked Traits
In males, there is no second X chromosome to “_______________” a recessive gene. If _____________ get an X with the disorder, they have it. _______________ must inherit defective X’s from _______________ parents.
What is the number inside of each circle?___________, ____________, ____________,____________
Example of Sex-Linked Trait
H = Normal blood clotting h = Hemophilia
Example of Sex-Linked Trait
Normal male:_______________________ Male with Hemophilia:______________________ Normal female (not a carrier for hemophilia – homozygous):__________________ Normal female (carrier for hemophilia – heterozygous): _____________________ Female with Hemophilia: __________________________
Sample Problems
1. XHXh x XHY
Chances of: Punnett Square
a. hemophiliac child?
b. hemophiliac son?
c. hemophiliac daughter?
d. daughter who is carrier?
2. A woman who is a carrier for hemophilia marries a hemophiliac man.
Chances of: Punnett Square
a. hemophiliac child?
b. hemophiliac son?
c. hemophiliac daughter?
3. A normal man marries a Homozygous normal woman.
Chances of: Punnett Square
a. Will any of their kids be hemophiliacs?
4. A normal woman (whose father is a hemophiliac) marries a hemophiliac man.
What are their genotypes?