Pedigrees Pedigrees A pedigree is a diagram of

Pedigrees

Pedigrees • A pedigree is a diagram of family relationships that uses symbols to represent people and lines to represent genetic relationships. • These diagrams make it easier to visualize relationships within families, particularly large extended families. • Pedigrees are often used to determine the mode of inheritance (dominant, recessive, etc. ) of genetic diseases.

Pedigrees Squares represent Males Circles represent Females Horizontal lines connecting a male and female represent mating Vertical lines extending downward from a couple represent their children • Oldest individuals are found at the top and youngest on the bottom • •

Pedigrees • Completely shaded in individuals posses the trait • Half shaded in individuals are carriers of the trait

Complete the handout

Complete the handout

Pedigree Problems • Brown eyes are dominant to blue eyes. John has blue eyes. His parents are heterozygous brown eyed individuals. When John was married, they had 3 children. The oldest girl had brown eyes, the middle son had blue eyes, and the youngest daughter had brown eyes. When the youngest daughter was married, she had twins. The male had blue eyes and his twin sister was homozygous for brown eyes. Construct a pedigree for the following individuals. Please write the genotypes where possible.

Pedigree Problems • The ability to taste PTC is controlled by a dominant gene (T). A woman nontaster marries a male taster. They have three children. The two boys were able to taste the paper and their younger sister was a nontaster. All the grandparents were tasters. Construct a pedigree of this family. (Please let nontasters (tt) be the shaded individuals)