Complex Patterns of Inheritance Incomplete/Codominance So far, we have learned about simple Mendelian inheritance--traits controlled by dominant and recessive paired alleles However, MOST alleles are not simply dominant or recessive

Incomplete Dominance Incomplete Dominance = The phenotype of the heterozygote is intermediate between those of the two homozygotes

Example: Snapdragons RR = Red

Example: Snapdragons RR = Red WW= White

Example: Snapdragons RR = Red WW= White RW = Pink

Example: Hair CC = Curly SS = Straight CS= Wavy Punnett square problem: 2 Wavy haired people have a child C S C S

Example: Hair CC CS SS CC = Curly SS = Straight CS= Wavy Punnett square problem: 2 Wavy haired people marry C S C 25% Curly S 50% Wavy 25% Straight CC CS SS

Practice Problem: Incomplete Dominance For each practice problem, draw the Punnett square and give the phenotype ratios A: Cross a pink snapdragon with a white snapdragon B: Cross a red snapdragon with a white snapdragon

Codominance Codominance = the heterozygote produces the phenotypes of BOTH homozygotes

Example: Blood Type

Example: Chickens BB = Black WW = White BW = Checkered

Other examples Cows: RR = Red WW= White RW=Roan (red and white spots) Horses: GG = Gray WW = White GW=Apaloosa (white with gray spots)

Example: Horses Punnett square problem: 2 appaloosa horses are crossed G W G W

Example: Horses GG GW WW Punnett square problem: 2 appaloosa horses are crossed G W G 25% Gray W 50% Appaloosa 25% White GG GW WW

Codominance Practice Problem For each practice problem, draw the Punnett square and give the phenotype ratios Cross a checkered chicken with a black chicken Cross two checkered chickens together

Output Activity Read the notes and glue them into your notebook (page 35) Complete the Baby Blunder activity and glue it into your notebook.