Complex Patterns of Inheritance IncompleteCodominance So far we

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 C S S

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

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 G W W

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

Codominance Practice Problem • For each practice problem, draw the Punnett square and give the phenotype ratios A. Cross a checkered chicken with a black chicken B. 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.