Pedigrees What are pedigree charts A pedigree for

Pedigrees

What are pedigree charts?

A pedigree for any family, be it dogs, cats or humans, shows the pattern of inheritance in a family for a specific trait. Males are shown as squares and females are shown as circles. = =

Each generation is shown as a Roman numeral and each person in a generation is numbered. The trait that is being expressed is shown as a shaded shape.

So, here we know that individual I 1 is a male that shows the trait. His daughter, II 1, also shows the trait. His sons, II 2 and II 3, do not show the trait.

Let’s do this together. . . Observe the pedigree. Number the generations and each person on the pedigree. I 1 1 1 2 2 2 3 4 3 II 5 In this family, how many individuals show the trait? six Which males show the trait? (generation, number) III 4 5 IV 1 2 II-5 III-2 III-3 IV-1

Determining genotypes N N N nn nn Start with what you know. nn N N nn nn N N In this case, N = normal feet n = webbed feet Since shaded show the trait, all shaded are homozygous recessive. And all unshaded have at least one dominant gene.

Determining genotypes N N N nn nn Looking at individual IV-1 and his parents. nn N N nn nn Nn N In order for him to be “nn”, he had to have inherited his recessive genes from his parents, since his parents don’t show the recessive trait, they both have to be _____? Nn it down. Write

Determining genotypes Keep working up that way. Nn nn What is the only possible genotype for II-4? Nn nn Nn Nn nn nn Nn nn What is the only possible genotype for I-1? Nn N This means that the rest are also. . .

Determining genotypes Keep working up that way. Nn nn Can you determine the genotype of individual IV-2? Nn Nn nn nn Nn N

Work with a partner Answer the rest of your sheet with a partner.