Sexlinked DisordersBiologySexLinked TraitsSexlinked traits are produced by genes only on the X chromosome They can be Dominant or RecessiveA dominant a recessiveWhat would be the genotypes of ID: 859115
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1 Human Genetics Sex - linked Disorders
Human Genetics Sex - linked Disorders Biology Sex - Linked Traits ï Sex - linked traits are produced by genes only on the X chromosome. ï They can be Dominant or Recessive. ï A = dominant a = recessive ï What would be the genotypes of a male and female that have a Sex - linked Dominant trait and do not express the trait? ï Expresses Trait: Male - X
2 A Y Female - X A X A or
A Y Female - X A X A or X A X a ï No Expression: Male - X a Y Female - X a X a ï What would be the genotypes of a male and female that have a Sex - linked Recessive trait and do not express the trait? ï Expresses Trait: Male - X a Y Female - X a X a ï No Expression: Male - X A Y Fe
3 male - X A X A
male - X A X A or X A X a (Carrier) ï Most Sex - linked traits are Recessive ! Sex - Linked Recessive Traits ï More males than females are affected. ï An affected son can have parents who have the normal phenotype. (X A Y x X A X a )
4 ï For a daughter to have the trait, he
ï For a daughter to have the trait, her father must also have it. Her mother must have it or be a carrier. ( X a Y , X a X a , X A X a ) ï The trait often skips a generation from the grandfather to the grandson. ï If a woman has the trait ( X a X a ), all of her sons will be affected. Examples of Sex - Linked Recessive Disorders ï Red/Green Colorblindness â Diff
5 iculty perceiving differences between c
iculty perceiving differences between colors (red or green, blue or yellow). ï Hemophilia â Absence of one or more proteins necessary for normal blood clotting. ï Deafness ï Cataracts â opacity in the lens that can lead to blindness Examples of Sex - Linked Recessive Disorders, continued⦠ï Night blindness â ( Nyctalopia ) rods do not work so that can n
6 ot see in the dark ï Glaucoma â
ot see in the dark ï Glaucoma â pressure in the eye that can lead to optic nerve damage and blindness ï Duchenne Muscular Dystrophy â progressive weakness and degeneration of skeletal muscles that control movement due to absence of dystrophin (protein that maintains muscle integrity). Mainly in boys, onset 3 - 5 yrs, by 12 years canât walk, and later needs respira