Co-dominance and Incomplete Inheritance 1.3 – Characteristics and Inheritance Page 21

Incomplete and Co-dominance

Incomplete Dominance When neither allele is dominant and they blend together to form a new phenotype. Each genotype has a different phenotype The heterozygous phenotype will be intermediate/blended between the two homozygotes. We use upper case letters for each colour eg: W = white and B= black therefore WB = grey

Example When red flowers are crossed with white flowers all of the offspring have pink flowers. What percent of the offspring will be red, white and pink if we cross two pink flowers?

Draw a punnet square to determine the % of offspring when two pink flowers are crossed R = red 25% R RR RW W = white 25% W RW WW 50% RW = pink

Co-dominance Neither allele is dominant and both are expressed in the phenotype of the heterozygote

Example When white bears mate with black bears, all the offspring have black and white spots.

What type of offspring will be produced if a black bear and a spotted bear are mated? B = black 50% B BB BB W = white 0% W BW BW BW = spots 50%

Complete Questions from your Genetics Booklet on pages 20,21,22 This is due Wednesday