Download Sex-Linked Traits

Sex-Linked Traits
Ch. 10.5
Sex-Linked Genes
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Sex chromosomes: X and Y
(male: XY, female: XX)
Offspring sex depends on whether the
sperm cell that fertilizes the egg carries
an X or a Y
Sex-linked gene = any gene that is
located on a sex chromosome (most
found on the X chromosome)
Discovery of Sex-Linked Genes
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Thomas Morgan
discovered sex-linked
genes while studying eye
color in fruit flies
White eyes are rare in
fruit flies (most have red
eyes)
White Eye Color
Inheritance in
Drosophila
Summary:
P: XRXR x XrY
F1: 2XRXr, 2XRY
F2: XRXR, XRXr, XRY, XrY
Conclusion: The gene
involved in eye color is on
the X chromosome!
Sex-Linked Disorders
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Color blindness, mostly in males
color blindness test
FYI:
– Achromatopsia - complete color blindness,
seeing only shades of gray
– Deuteranopia - difficulty telling the difference
between red/purple and green/purple
– Protanopia - difficulty telling the difference
between blue/green and red/green
– Tritanopia - difficulty telling the difference
between yellow/green and blue/green)
Sex-Linked Disorders
Continued…
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Hemophilia, (blood
fails to clot)
Much more common
in males!