1. Incomplete and Co-Dominance

2. Incomplete Dominance
One allele is not completely dominant over the other.
The heterozygous phenotype is in-between the homozygous phenotypes.

3. Incomplete Dominance
If you cross a RED flower with a WHITE flower, you will get a PINK flower.
NOTICE:
the RED genotype is RR
the WHITE genotype is WW the PINK genotype is RW

4. Let’s Practice! BW BW BW BW
Cross a BLACK chicken (BB) with a WHITE chicken (WW). These alleles show INCOMPLETE DOMINANCE. B B
What percent is black? White? Gray? BW BW W
Black: 0%
White: 0%
Gray: 100% BW BW W

5. Let’s Practice! BW BW BW BW
Cross a BLACK chicken (BB) with a WHITE chicken (WW). These alleles show INCOMPLETE DOMINANCE. B B
What is the genotype and phenotype of the F1 generation? BW BW
Genotype: BW
Phenotype: Gray W BW BW W

6. Let’s Practice! BB BW BW WW
What would the cross look like if you crossed two GREY chickens (BW). These alleles show INCOMPLETE DOMINANCE. B W
Genotype:
1 BB
1 WW
2 BW
Phenotype:
1 Black
1 White
2 Gray
What is the genotype and phenotype of the F2 generation? BB BW B BW WW W

7. Mrs. Smith and Ms. K’s Memory Trick
INcomplete is INbetween

8. Co-Dominance Both alleles contribute to the phenotype.
For Example: In chickens, the allele for black feathers is co-dominant with the allele for white feathers. These chickens will have BOTH black and white feathers.

9. Let’s Practice! BW BW BW BW
Cross a Black chicken (BB) with a White chicken (WW). These alleles show CO-DOMINANCE. B B
How many chickens in the F1 generation are completely black? White?
Black and white? BW BW W
Black: 0%
White: 0%
Both: 100% BW BW W

10. Let’s Practice! BW BW BW BW
Cross a Black chicken (BB) with a White chicken (WW). These alleles show CO-DOMINANCE. B B
What is the genotype and phenotype of the F1 generation?
Genotype: BW
Phenotype: Black and white or checkered. BW BW W BW BW W

11. Let’s Practice! BB BW BW WW
Cross two Black and White (checkered) chickens (BW). These alleles show CO-DOMINANCE. B W
Genotype:
1 BB
1 WW
2 BW
Phenotype:
1 Black
1 White
2 Checkered
List all possible genotypes and phenotypes of the F2 generation. BB BW B BW WW W

12. Mrs. Smith and Ms. K’s Memory Trick
COdominant alleles COllaborate together

13. If you need more help…
READ PAGE 272