Pedigrees Objective: E5 - Explain how pedigrees are used to study inheritance of traits

What is a Pedigree? Sounds like a dog food. It is a diagram that shows how a trait is inherited through several generations. ◦Squares = males ◦Circles = females ◦Shaded = individual has the trait or condition ◦Unshaded = individual does not have trait or condition ◦horizontal line = marriage ◦vertical line = offspring, arranged from left to right in order of birth ◦Roman numerals - label different generations

Patterns of Inheritance By analyzing patterns of inheritance, biologists can learn about genetic diseases. If a trait is autosomal, it will appear in both sexes equally and if it is sex-linked, it is usually seen only in males. The major use of pedigree analysis is in clinical evaluation and counseling of patients with inherited abnormalities. (Chromosomes 1-22) (23 rd pair)

Human geneticists illustrate the inheritance of a gene within a family by using a pedigree chart. Pedigree for the Albino Trait Pedigree for a Sex Linked Trait

Albanism Fraction of genotypes- ½ Aa, ½ aa Ratio of genotypes- 2:2 Fraction of phenotypes- ½ albino, ½ normal Ratio of phenotypes- 2:2

Practice Pedigree for the Albino Trait aa A _ a a a aa a aaaa a a