1. Bell Work
In dogs, erect ears is dominate over droopy ears. What are the results if two heterozygous dogs have a litter of puppies.
Genotype:
Phenotype:

2. Punnett Squares with Co and Incomplete Dominance
Biology – Lecture 49
Punnett Squares with Co and Incomplete Dominance

3. Genetics Vocabulary
Incomplete dominance - expressing an intermediate phenotype
Co-dominance - expressing both alleles at once

4. In Both Situations Neither trait is dominant over the other one.
A middle or hybrid trait is achieved.
Each trait can get its own letter or one trait can be capital regular and the other can be capital prime.
Neither letter can be lowercase because neither trait is recessive.

5. Incomplete Dominance
This is when the heterozygous genotype is “in between” the two homozygeous genotypes.
Neither phenotype is actually shown.

6. Example of Incomplete Dominance
Height
Short (SS), Medium (TS), Tall (TT)
Hair Color
Black Hair (BB), Brown Hair (BB’), Blonde Hair (B’B’)

7. Co-dominance
An organism that has both alleles of a gene and displays both phenotypes at the same time.
It is not an “in-between” trait, but rather that both traits are shown.

8. Examples of Co-Dominance
The fur of animals
Black Fur (BB), Speckled Fur (BT), Tan Fur (TT)

9. Example Problems
In humans, wavy hair (CS) results by the co-dominant situation of curly hair (C) and straight hair (S).  What are the possible results if a curly-haired man and wavy-haired woman have children.  

10. In iris, purple (P) is incompletely dominant over white (W)
In iris, purple (P) is incompletely dominant over white (W). What would be the results of a cross if both parents were pale lavender?

11. In crocus flowers, white (W) and purple (P) colors are co-dominant, and result in a purple and white striped flower when both genes are present.  What are the possible results from the cross-pollination of a striped crocus with a white crocus?

12. In cattle, red (R) is incompletely dominant over white (W) hides
In cattle, red (R) is incompletely dominant over white (W) hides.  Roan in the name of the color that results from incomplete dominance.  What are the possible results if a white male mates with a roan female? 

13. Black hair is homozygous dominant. Brown hair is heterozygous
Black hair is homozygous dominant. Brown hair is heterozygous. Blonde hair is homozygous recessive. (This is an example of incomplete dominance.) A woman with brown hair marries a man with brown hair. What are genotypes and phenotype possibilities for their kids?

14. Height is an example of incomplete dominance
Height is an example of incomplete dominance. The alleles are as follows: T=tall (5’11”-6’2”); TS=medium height (5’4”-5’10”) S=short (5’3” or smaller).
If Mom is 5’5”, and Dad is 6’0”, what are the possible height outcomes of their children?

15. A cross between red-flowered snapdragons and white-flowered snapdragons produces offspring with pink flowers. Is this co-or incomplete dominance? Show the punnett square and the genotype/phenotype.

16. Using the previous example, suppose a pink-flowered plant is crossed with a pink-flowered plant. What is the genotype and phenotype of the offspring?

17. There are three possible genotypes and phenotypes for wing color in a species of moth: RR = red wings; RY = orange wings; YY = yellow wings.
What are the genotypes and phenotypes of a cross between an orange winged moth and a yellow winged moth?

18. A tabby cat (co-dominant black/tan) is crossed with a tan cat
A tabby cat (co-dominant black/tan) is crossed with a tan cat. What are the possible outcomes of their children?

19. In a fictional species of mice, one gene determines fur color
In a fictional species of mice, one gene determines fur color. Let B = black fur and W = white fur. If this is co-dominance, what will the offspring look like? If this is incomplete dominance, what will the offspring look like?