Pedigrees

Pedigrees help us to track certain traits in our family tree. When making a pedigree: =Female =Male A filled in shape means they have the disorder/trait A half filled shape means they are a carrier An empty shape means they don’t have the gene for the disorder/trait.

Color Blindness Pedigree Which are carriers? What is the genotype of each person?

Reading Pedigrees If it were dominant- could gen. II have an affected person? Must be recessive. Which ones are carriers?

Reading Pedigrees If it were dominant? Must be recessive. Which are carriers?

Reading Pedigrees If dominant? Must be recessive.

Reading Pedigrees If dominant? If recessive? Must be dominant.

Reading Pedigrees Notice anything interesting? Sex-linked- recessive

Patterns Why are most negative traits recessive? –Evolution! If negative traits were dominant it would lower the reproductive fitness of an organism and the trait would die with that individual. Recessive traits can hide in an organism allowing it to be passed on.