1. 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

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

3. Example: Snapdragons
RR = Red

4. Example: Snapdragons
RR = Red
WW= White

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

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

7. 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 % Wavy
25% Straight CC CS SS

8. 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

9. Codominance
Codominance = the heterozygote produces the phenotypes of BOTH homozygotes

10. Example: Blood Type

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

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

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

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

15. 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

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