Transcript 2 Pedigrees
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 Trait: Falconi anemia Forms of the trait: -The dominant form is normal bone marrow function - in other words, no anemia. -The recessive form is Falconi anemia. Individuals affected show slow growth, heart defects, possible bone marrow failure and a high rate of leukemia. A typical pedigree for a family that carries Falconi anemia. Note that carriers are not indicated with half-colored shapes in this chart. nn Nn nn N? Nn nn Nn Nn Nn nn Nn N? N? Trait: Neurofibromatosis Forms of the trait: The dominant form is neurofibromatosis, caused by the production of an abnormal form of the protein neurofibromin. Affected individuals show spots of abnormal skin pigmentation and non-cancerous tumors that can interfere with the nervous system and cause blindness. Some tumors can convert to a cancerous form. The recessive form is a normal protein - in other words, no neurofibromatosis. Nn nn nn nn Nn Nn Nn Nn nn nn nn N? nn 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) According to directions to shade nontasters… If you actually shaded “tasters”…