Pedigree Charts How to work Dominant and Recessive Genetic Problems with a Pedigree Chart

Pedigree Charts Besides showing possible gene pairings, a pedigree chart gives the probability of each pairing. It shows how often, on the average, a given pairing will occur.

Pea Plant Characteristics

Show a cross between a tall and short pea plant Step One Write down the set of contrasting traits. Assign the capitol letter to the dominant trait and the lower case letter to the recessive trait. Tall Short T t

Show a cross between a tall and short pea plant Step Two Write down possible genotypes and phenotypes. TT Tt tt Tall Short

Show a cross between a tall and short pea plant Step Three Fill in the genotypes of the parents on the pedigree chart.

Pedigree Chart P1 P2 F1

Parents In the circle - the possible gametes of the female are listed. TT tt P1 P2 In the circle - the possible gametes of the female are listed. In the square - the possible gametes of the male are listed

Show a cross between a tall and short pea plant Step Four Fill in the genetic possibilities of the F1 on the pedigree chart.

Cross between a tall and short pea plant TT tt P1 P2 Tt F1 Take first gene from the female and first gene from the male and place in the first offspring spot.

Cross between a tall and short pea plant TT tt P1 P2 Tt Tt F1 Take first gene from the female and second gene from the male and place in the second offspring spot.

Cross between a tall and short pea plant TT tt P1 P2 Tt Tt Tt F1 Take second gene from the female and first gene from the male and place in the third offspring spot.

Cross between a tall and short pea plant TT tt P1 P2 Tt Tt Tt Tt F1 Take second gene from the female and second gene from the male and place in the fourth offspring spot.

Show a cross between a tall and short pea plant Step Five Write down the genotypic ratio and the phenotypic ratio. Purebred dominant : Hybrid : Purebred recessive Tall : Short

Cross between a tall and short pea plant TT tt P1 P2 Tt Tt Tt Tt F1 0:4:0 Genotypic Ratio 4:0 Phenotypic Ratio

Pedigree A pedigree is a visual tool for following a trait through generations of a family. F1 F2

Pedigree Males are represented by squares and females by circles. Male

Pedigree A completely filled circle or square shows that the trait is seen in that person. Half-colored circles or squares indicate carriers. A carrier is heterozygous for the trait, and it is not seen. An empty circle or square means they do not have the trait and they are not carriers