Incomplete Dominance Incomplete Dominance: The heterozygous genotype produces a phenotype that falls in between the dominant trait and the recessive trait.

Example: In flowers, petal color demonstrates incomplete dominance. Red results when a flower has homozygous dominant alleles for the trait. White results when a flower has homozygous recessive alleles for the trait. A flower that is heterozygous for this trait will be pink. Predict the genotypic and phenotypic ratios of the offspring for the following: 1. Red and white RR x rr Genotypic Ratio: 100% Rr Phenotypic Ratio: 100% pink flowers R R Rr r

Example: In flowers, petal color demonstrates incomplete dominance. Red results when a flower has homozygous dominant alleles for the trait. White results when a flower has homozygous recessive alleles for the trait. A flower that is heterozygous for this trait will be pink. Predict the genotypic and phenotypic ratios of the offspring for the following: 2. Red and pink RR x Rr Genotypic Ratio: 50% RR 50% Rr Phenotypic Ratio: 50% Red flowers, 50% Pink flowers R R RR Rr R r

Rr rr RR Rr rr White and Pink rr x Rr r r R r Pink and Pink Rr x Rr Genotypic Ratio: 50% Rr 50% rr Phenotypic Ratio: 50% Pink flowers 50% White flowers r r Rr rr R r Pink and Pink Rr x Rr Genotypic Ratio: 25% RR 50% Rr 25% rr Phenotypic Ratio: 25% Red flowers 50% Pink flowers 25% White flowers R r RR Rr rr R r

Codominance Codominance: condition in which both alleles of a gene are expressed in heterozygous offspring.

Example 1: In cows black coat color and white coat color are codominant. Heterozygous offspring will be spotted. Black cow and White cow BB x WW B B Genotypic Ratio: 100% BW Phenotypic Ratio: 100% Spotted cow BW W

Example 1: In cows black coat color and white coat color are codominant. Heterozygous offspring will be spotted. 2. Black cow and Spotted cow BB x BW B B Genotypic Ratio: 50% BB 50% BW Phenotypic Ratio: 50% Black cow 50% Spotted cow BB BW B W

Example 1: In cows black coat color and white coat color are codominant. Heterozygous offspring will be spotted. 3. Both Spotted cows BW x BW Genotypic Ratio: 25 % BB 50% BW 25% WW Phenotypic Ratio: 25% Black cow 50% Spotted cow 25% White cow B W BB BW WW B W

Blood Type (phenotype) Example 2: In blood typing, the gene for type A and the gene for type B are codominant. The gene for type O is recessive. Blood Type (phenotype) Genotype A AA or AO B BB or BO AB O OO

AO Determine the possible blood types of the offspring when: 1. Mother is type O, Father is type A (homozygous) O O Genotypic Ratio: 100% AO Phenotypic Ratio: 100% Type A Blood AO A

AA AB AO BO Determine the possible blood types of the offspring when: 2. Mother is type AB, Father is Type A (heterozygous) Genotypic Ratio: 25 % AA 25% AO 25% AB 25% BO Phenotypic Ratio: 50% Type A Blood 25% Type AB Blood 25% Type B Blood A B AA AB AO BO A O

AB BO AO OO Determine the possible blood types of the offspring when: 3. Mother is type A (heterozygous), Father is type B (heterozygous) Genotypic Ratio: 25 % OO 25% AO 25% AB 25% BO Phenotypic Ratio: 25% Type O Blood 25% Type A Blood 25% Type AB Blood 25% Type B Blood A O AB BO AO OO B O

AB Determine the possible blood types of the offspring when: 4. Mother is type B (homozygous), Father is type A (homozygous) B B Genotypic Ratio: 100% AB Phenotypic Ratio: 100% Type AB Blood AB A