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

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

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

Parts of a Pedigree Male with trait Unaffected female Marriage line Unaffected Female carries allele Male doesn’t show trait First generation Second generation

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

Color Blindness Cause: sex-linked recessive 1/100 males have, 1/1000 females Can’t see red-green, or blue due to a missing protein.                                           

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

X-linked Inheritance pedigree chart

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.

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

The very tragic disease… hairy ears symptoms…hairy ears Only 1 cure known….

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

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

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

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

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

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

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

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

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

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