1. KEY CONCEPT Phenotype is affected by many different factors.

2. Phenotype can depend on interactions of alleles.
In incomplete dominance, neither allele is completely dominant nor completely recessive.
Heterozygous phenotype is intermediate between the two homozygous phenotypes
Heterozygous is like a “blend”

3. List the genotypes. 4RW List the phenotypes. 4 Pink W W R W R W R pink
Example: Cross a homozygous red carnation flower (RR) with a homozygous white flower (WW).
List the genotypes.
4RW
List the phenotypes.
4 Pink
W W R W R W R
pink
pink R W R W
pink
pink

4. List the genotypes. 2RW, 2WW List the phenotypes. 2 Pink, 2White R W R
Example: Cross one heterozygous pink (RW) 4 o’clock flower with a White flower (WW).
List the genotypes.
2RW, 2WW
List the phenotypes.
2 Pink, 2White
R W R W W W W
pink
white R W W W
pink
white

5. Codominance red white roan
Defined: When both alleles are dominant and equally expressed
The colors do NOT blend together, but are equally seen
Ex: Cattle Coat
Red cow x White cow =
Roan Cow
Ex: Human Blood types
Type A x Type B = Type AB
red
white
roan

6. Blood types are another example of codominance.
The ABO blood types result from codominant alleles
This blood group consists of 3 different alleles
Dominant A allele
Dominant B allele
Recessive O allele
A and B are equally
dominant
Many genes have more than two alleles.

7. B B A A B A B A B A B List the genotypes. 4AB List the phenotypes.
Ex: Cross Jason who is homozygous for type A blood with Maria who is homozygous for type B blood.
List the genotypes.
4AB
List the phenotypes.
4 type AB blood
B B A A B A B A B A B

8. B o A o A B A o B o o o List the genotypes. 1AB, 1Ao, 1Bo, 1oo
Ex: Cross Mike who is heterozygous for type A blood with Lisa who is heterozygous for type B blood.
List the genotypes.
1AB, 1Ao, 1Bo, 1oo
List the phenotypes.
1 type AB blood
1 type A blood
1 type B blood
1 type o blood
Probability of Heterozygous individual?
75%
B o A o A B A o B o o o

9. Many genes may interact to produce one trait.
Polygenic traits are produced by two or more genes.
Order of dominance: brown > green > blue.

10. An epistatic gene can interfere with other genes.
This is like a “knock out” gene

11. The environment interacts with genotype.
Phenotype is a combination of genotype and environment.
The sex of sea turtles depends on both genes and the environment
Height is an example of a phenotype strongly affected by the environment.