1. EQ: What are incomplete and codominance?
Warmup:

2. Complete Dominance
If we cross a tall pea plant and a short pea plant what do we get?
Tall.
The tall hides the short.
Dominant completely hides recessive
Which one is dominant and which one is recessive?

3. Complete Dominance dominant gene totally masks the recessive
Mendel investigated complete dominance
dominant gene totally masks the recessive

4. Review Problem: Dominant/Recessive
In pea plants, purple flowers (P) are dominant over white flowers (p) show the cross between two heterozygous plants.
P p
GENOTYPES:
- PP (1); Pp (2); pp (1)
- ratio 1:2:1 P p PP Pp
PHENOTYPES: Pp pp
- purple (3); white (1)
- ratio 3:1

5. Exceptions to Mendelian Inheritance

6. Incomplete dominance
What happened when we crossed a red and white flower?
Why?
Whats dominant and what’s recessive?
Is the dominant totally

7. Incomplete Dominance
A cross between two different phenotypes can produce offspring a blending of the parental traits. 

8. Incomplete Dominance It's like mixing paints
Red + white will make pink
Red doesn't totally dominate the white, instead there is incomplete dominance, and we end up with something in-between.

9. Incomplete Dominance

10. Incomplete Dominance
How to recognize a question involving incomplete dominance:
the offspring show a 3rd phenotype. 
the offspring are different from the parents.
the trait in the offspring is a blend of the parental traits.

11. Incomplete Dominance
Can still use the Punnett square to solve problems involving incomplete dominance. 
The letters used to represent each allele will be different, lowercase letters
Why lowercase?
Because neither allele dominates the other

12. 2 homozygous parents still produce 100% heterozygotes!
Incomplete Dominance r r
r = red flowers w = white flowers
rw = pink flowers
Cross red and white flowered plants
Results?
Genotype: 100% rw
Phenotype: 100% pink rw rw w rw rw w
2 homozygous parents still produce 100% heterozygotes!

13. Same as when two heterozygotes mated before
Incomplete Dominance
A cross between a blue bird & a white bird produces offspring that are silver. 
What are the genotypes of the parent birds in the cross?
b= blue
w= white
What is/are the genotype(s) of the silver offspring? bw
What would be the phenotypic percent of offspring produced by two silver birds?
25% blue
25% white
50% silver
bb x ww
b w bb bw ww b w
1 : 2 : 1 ratio
Same as when two heterozygotes mated before

14. ry x ry Incomplete Dominance
When two plants with orange fruits are crossed the following phenotypic ratios are present in the offspring: 25% red fruit, 50% orange fruit, 25% yellow fruit. 
What are the genotypes of the parent orange-fruited plants?
1 : 2 : 1
ry x ry

16. Codominance
What happened when we crossed lentils with big spots with lentils that had small dots.
Both showed up…Why? Did the big spots dominate the small spots?
Which one is dominant?

17. red x white = red & white spotted
Co-dominance
Prefix "co-" means "together“
Cooperate = work together
Coexist = exist together
The heterozygous organism has a third phenotype in which both of the parental traits appear together. (Not blended).
red x white = red & white spotted

18. Co-dominance
A very very very very very common phenotype used in questions about co-dominance is roan fur in cattle. 
Cattle can be red, white or roan (red & white hairs together). 

19. Co-dominance
Can still use the Punnett square to solve problems involving co-dominance. 
The letters used to represent each allele will be different, CAPITAL letters
RR = all red hairs
WW = all white hairs
RW = red & white hairs together.

20. Co-dominance How to recognize a question involving co-dominance:
Notice that the offspring show a 3rd phenotype.  The parents each have one, and the offspring are different from the parents.
Notice that in the offspring BOTH of the parental traits are expressed, not a mix.

21. Codominance R=roan (reddish Brown) W= White
Cross a homozygous white cow with a homozygous roan. What is the phenotypic ratio?

22. Co-dominance
Predict the phenotypic ratios of offspring when a homozygous white cow is crossed with a roan bull.
50% WW - White
50% WR - Roan
What should the genotypes & phenotypes for parent cattle be if a farmer wanted only cattle with red fur?
Both parents should be RR, red
W W W R WW WR

23. Co-dominance
A cross between a black (BB) cat & a tan (TT) cat produces a tabby (BT) pattern (black & tan fur together).
What pattern of inheritance does this illustrate?
Co-dominance
What percent of kittens would have tan fur if a tabby cat is crossed with a black cat?
0% tan
50 % Tabby
50% Black
B B B T BB BT

24. Codominance Sickle Cell Anemia is also co-dominant.
Having sickle cell disease makes your red-blood cells sickle-shaped instead of circular.
They can’t carry as much oxygen, which can leave tissues oxygen deprived (anemia) = pain!
The disease is recessive, but co-dominant because heterozygotes also have a mild form of the disease.
SS= No disease
Ss = Sickle Cell Trait (mild form)
ss= Sickle Cell

25. Codominance NS = some of each SS = sickle cells NN = normal cells sick
The heterozygous condition, both alleles are expressed equally
Sickle Cell Anemia in Humans
NS = some of each
SS = sickle cells
NN = normal cells
sick

26. Problem: Codominance S NS SS N S GENOTYPES: - NS (2) SS (2)
Show the cross between an individual with sickle-cell anemia and another who is a carrier but not sick.
N S
GENOTYPES:
- NS (2) SS (2)
- ratio 1:1 S NS SS
PHENOTYPES:
- carrier (2); sick (2)
- ratio 1:1

27. Summary What is Codominance? What is incomplete dominance
When two dominant traits both show up at the same time.
What is incomplete dominance
When two traits BLEND and neither is dominant.

28. PURE GOLD Breeding a pure brown with a pure white… BB x WW W W B BW BW
Genotype
% BB
% WW
% BW
W W B BW BW
100
Phenotype
% Brown
% White
% Palomino BW BW
100

29. Coat color genes in mammals
Multiple Genes
Coat color genes in mammals

31. More complications
Polygenic traits- determined by effects of two or more genes
Pleiotropy- gene has multiple effects on phenotype
Epistasis - one gene affects the expression of another
Phenotypic plasticity – environment influences phenotype

32. Epistatic effect of locus C on locus B
Allele C permits synthesis of dihydroxyindole
cc can’t make dihydroxyindole
Locus B enzyme converts brown dihydroxyindole to black eumelanin

33. Phenotypic plasticity
soil pH affects Hydrangea flower color