Notes sex linked traits

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Notes sex linked traits

  1. 1. Notes: Sex-Linked Traits (pg 16)
  2. 2. Notes: Sex-Linked Traits (pg 16)• Sex-Linked Trait = Traits controlled by genes located on sex chromosomes
  3. 3. Notes: Sex-Linked Traits (pg 16)• Sex-Linked Trait = Traits controlled by genes located on sex chromosomes• Females = XX, Males = XY
  4. 4. Notes: Sex-Linked Traits (pg 16)• Sex-Linked Trait = Traits controlled by genes located on sex chromosomes• Females = XX, Males = XY• The X chromosome is large and contains about 2000 genes. The Y chromosome is very small and has only86genes.
  5. 5. Notes: Sex-Linked Traits (pg 16)• Sex-Linked Trait = Traits controlled by genes located on sex chromosomes• Females = XX, Males = XY• The X chromosome is large and contains about 2000 genes. The Y chromosome is very small and has only86genes.• Genotypes written as XAXA (females) and XAY (males)
  6. 6. • Discovered by Thomas Hunt Morgan in 1907 while studying fruit flies
  7. 7. • Discovered by Thomas Hunt Morgan in 1907 while studying fruit flies• He crossed a white-eyed female (XrXr) with a red eyed male (XRY)
  8. 8. • Discovered by Thomas Hunt Morgan in 1907 while studying fruit flies• He crossed a white-eyed female (XrXr) with a red eyed male (XRY)XrXrXRY
  9. 9. • Discovered by Thomas Hunt Morgan in 1907 while studying fruit flies• He crossed a white-eyed female (XrXr) with a red eyed male (XRY)XrXr XR Xr X RX rXR X rY XrYY
  10. 10. • Discovered by Thomas Hunt Morgan in 1907 while studying fruit flies• He crossed a white-eyed female (XrXr) with a red eyed male (XRY)XrXr XR Xr X RX r Females: 100%XR Red eyed Males: 100% X rY XrY White eyedY
  11. 11. Sex-Linked Disorders• Males are more likely to be affected, because females must inherit 2 bad copies of a gene to be affected, while males only need 1 bad copy
  12. 12. Sex-Linked Disorders• Males are more likely to be affected, because females must inherit 2 bad copies of a gene to be affected, while males only need 1 bad copy• Example: Color Blindness (b) is recessive to normal vision (B). Color blind female = XbXb Color blind male = XbY
  13. 13. Sex-Linked Disorders• Males are more likely to be affected, because females must inherit 2 bad copies of a gene to be affected, while males only need 1 bad copy• Example: Color Blindness (b) is recessive to normal vision (B). Color blind female = XbXb Color blind male = XbY• A woman who is XBXb is called a carrier: she has normal vision, but can have colorblind children
  14. 14. Sex-Linked Disorders• Males are more likely to be affected, because females must inherit 2 bad copies of a gene to be affected, while males only need 1 bad copy• Example: Color Blindness (b) is recessive to normal vision (B). Color blind female = XbXb Color blind male = XbY• A woman who is XBXb is called a carrier: she has normal vision, but can have colorblind children• Other sex-linked disorders: Hemophilia, muscular dystrophy, baldness
  15. 15. Output (pg 17)Practice Problem 1 Hemophilia is a recessive sex-linked disease. A woman who is a carrier for hemophilia (XHXh) has a child with a normal man (XHY). Draw the Punnett square and give the phenotype ratios for males and females separately.
  16. 16. Output (pg 17)Practice Problem 2 A woman who is a carrier for hemophilia has a child with a man who has hemophilia.

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