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Sex-linked traits §Sex-linked genes found on X chromosome § males have one X & Y – genes on X will be shown in males, even if recessive. Y chromosome X.

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Presentation on theme: "Sex-linked traits §Sex-linked genes found on X chromosome § males have one X & Y – genes on X will be shown in males, even if recessive. Y chromosome X."— Presentation transcript:

1 Sex-linked traits §Sex-linked genes found on X chromosome § males have one X & Y – genes on X will be shown in males, even if recessive. Y chromosome X chromosome

2 Sex-linked inheritance:, N = allele for normal color vision n = allele for color blindness normal male x normal vision female (carries allele) X N y XNXnXNXn XN XNXN XN X N X n X n y Normal female Normal female (carries c.b. allele) Normal male Affected male

3 Pedigrees §Pedigrees show how a trait is inherited through generations. §used to determine phenotypes and genotypes.

4 Parts of a Pedigree Male with trait Unaffected female Marriage line Unaffected Female carries allele Male doesnt show trait First generation Second generation

5 male or female? Normal Vision = N Color blindness = n is color blind? what genotype? what phenotype? what genotype? what phenotype? what genotype? Male Nope N Normal vision n color blindness Nn

6 Color Blindness §Cause: sex- linked recessive §1/100 males have, 1/1000 females §Cant see red- green, or blue due to a missing protein.

7 Hemophilia Sex-linked recessive approx. 1/10,000 boys Protein needed for blood clotting is missing. Affected person can bleed to death from cuts and bruises. Treated with transfusions of missing protein

8 X-linked Inheritance pedigree chart

9 Duchenne Muscular Dystrophy Sex-linked disorder causes loss of muscles & death (before age 20) Protein needed for muscle development missing. Affects 1 in 3000 males.

10 A very disabling condition in men Found on the Y-Chromosome

11 The very tragic disease… hairy ears §symptoms…hair y ears Only 1 cure known ….

12

13 Summary Questions On what chromosome are the genes found that causes color blindness, hemophilia, and Duchenne muscular dystrophy? a - Y-chromosome c – 1 st chromosome b - X-chromosome d – 23 rd chromosomes

14 Summary Questions On what chromosome are the genes found that causes color blindness, hemophilia, and Duchenne muscular dystrophy? a - Y-chromosome c – 1 st chromosome b - X-chromosome d – 23 rd chromosomes

15 Compared to females, males have a- two X chromosomes b- less chance of having hemophilia c- greater chance of being color blind d- 22 pairs of chromosomes

16 Compared to females, males have a- two X chromosomes b- less chance of having hemophilia c- greater chance of being color blind d- 22 pairs of chromosomes

17 Males tend to show sex-linked traits because a- sex-linked traits are codominant b- males have only one X chromosome c- females have incomplete dominance d- males have two X chromosomes

18 Males tend to show sex-linked traits because a- sex-linked traits are codominant b- males have only one X chromosome c- females have incomplete dominance d- males have two X chromosomes

19 A sex-linked condition causing muscle loss and early death a- hemophilia b- multiple sclerosis c- muscular dystrophy d- playing video games

20 A sex-linked condition causing muscle loss and early death a- hemophilia b- multiple sclerosis c- muscular dystrophy d- playing video games

21 From whom do men inherit sex-linked traits such as hemophilia and Duchenne muscular dystrophy from? a- from both mom and dad b- from dad only c- from mom only d- from grand parents

22 From whom do men inherit sex-linked traits such as hemophilia and Duchenne muscular dystrophy from? a- from both mom and dad b- from dad only c- from mom only d- from grand parents


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