1. 4/11/ 12 Bell Ringer What does incomplete dominance mean?
If I had a Red Homozygous Flower and a White Homozygous Flower, what would the Heterozygous Flower look like in incomplete dominance?
If I had a Dark Brown Homozygous Horse and a White Homozygous Horse, what would the Heterozygous Horse look like in incomplete dominance?

2. Homozygous Heterozygous Homozygous
Incomplete Dominance
When one allele is not completely dominant over another.
Heterozygous phenotype is between the two homozygous phenotypes.
Homozygous Heterozygous Homozygous

3. RR
R’R’ R R’
RR’ x

4. Now you try one
A Heterozygous snapdragon flower is crossed with another Heterozygous snapdragon flower. What Genotypes and Phenotypes could the offspring potentially have? x
RR’
RR’

5. R R R’ R’ R R’ 25% RR 50% R R’ 25% R’ R’ 25% Red 50% Pink 25% White R’

6. Codominance When two dominant alleles are expressed at the same time.
The phenotypes of both homozygotes are produced in heterozygotes.

7. x BB WW B W BW

8. Now you try one
A Heterozygous Chicken is crossed with a Homozygous White Chicken. What Genotypes and Phenotypes could the offspring potentially have? BW WW

9. W B WW BW
50% BW
50% WW
50% Checkered
50% White

10. Multiple Alleles
Some traits can have multiple alleles that control what phenotype an organism will have. B
= Dominant to b but recessive to B A B
= Dominant b
= Recessive to both of the other alleles A

11. Multiple Alleles In Humans
BLOOD TYPING:
Single gene that has multiple alleles O A B AB

12. How is a person’s blood type determined?
By the presence or absence of large molecules (Antigens) on the red blood cells.
Antibodies (part of our immune system) react with foreign antigens so it is important for doctors to know their patients blood type.

14. There are 3 alleles for blood type
ABO Blood Group
HUMAN BLOOD TYPES
PHENOTYPE
GENOTYPE A
AA or AO B
BB or BO AB O OO
There are 3 alleles for blood type
A, B, and O

15. A is dominant to O B is dominant to O A and B are Codominant
HUMAN BLOOD TYPES
PHENOTYPE
GENOTYPE A
AA or AO B
BB or BO AB O OO
There are 3 alleles for blood type:
A, B, and O
A is dominant to O B is dominant to O A and B are Codominant

16. How many different allele combinations are there for Blood Type?AA AB AO BB BO OO

17. A person with the blood type AA is crossed with a person with the blood type BB. What blood types could their offspring have?

18. A B AB

19. One parent has the blood type A and the other blood type B
One parent has the blood type A and the other blood type B. What are the genotypes of the parents if they produce children with only blood type AB?
Parents Phenotype
Parents Genotype
Type A
Type B or
A A
A O
B B
B O

20. A B AB A O B BO AB A O B AO AB A O B OO AO AB BO