Sex Linked Genes By: Jill Ziehm and Sierra Barker

Problem Question Sally is married to Joe who has a normal XY genotype. Sally’s sister is a carrier of muscular dystrophy and her two brothers do not have it. Which of her parents has muscular dystrophy? What is Sally’s genotype? What will the possible genotypes of Sally and Joe’s children be?

Steps to Solve Step 1: Create a pedigree chart to organize the information to find out what you don’t know

Step 2 Use punnett squares to solve for unknown alleles

Step 2 Grandparents Combine the letters in the square to create the genotypes After solving Sally’s parents genotype now you have found Sally’s genotype XX m XY X XmXm Y

Step 3 Parents By combining the information found in the last step to find Sally’s genotype you can now combine her genotype with Joe’s XX m XX XmYXmYXY XmXm X X Y

Step 4 Sally and Joe’s Kids The genotypes consist of 25% XX, 25% XY, 25% X m Y, and 25% XX m XX m XX XmYXmYXY XmXm X X Y