1. WarmUP
In Labrador retrievers, yellow is incompletely dominant to black. The heterozygous phenotype is chocolate. Cross a yellow lab with a chocolate lab.

2. Codominance A cross between organisms with two different phenotypes
Ex: Red x White
Produce offspring with a third phenotype that displays BOTH traits at the same time
Ex: Red and White Striped

3. Codominance
C. EXAMPLE: If a homozygous red flowered snap dragon plant (RR) is crossed with a homozygous white flowered snap dragon plant (WW), all of the F1 offspring will have Red and white flowers.
RED flower x WHITE flower  RED & WHITE flower

4. Codominance Andalusian chickens also show this pattern of inheritance.
If you cross a black (BB) chicken
With a white (WW) chicken
You get black+white speckled (BW) chicken

5. Human Codominance Sickle-Cell Anemia
An individual who is heterozygous (change in notes) for sickle-cell alleles will express BOTH normal and abnormal shaped blood cells
The oxygen carrying protein hemoglobin differs by one amino acid than the regular cause the shape to change: Normal RBC are disk shaped and abnormal are half moon or sickle shaped.
Abnormally shaped blood cells slow blood flow, block vessels, and result in tissue damage and pain.
Heterozygous individuals are said to have the sickle-cell trait because they show signs of sickle-cell related disorders if the availability of oxygen is reduced.
Normal red blood cell
Sickle cell

6. Human Codominance Blood Types
Blood type is determined by multiple alleles. This means there are more than two types of alleles possible that can make up a paring.
Allele A: red blood cells produce A antigens (protein) on the outside of the cell
Allele is expressed IA because it is dominant
Allele B: red blood cells produce B antigens (protein) on the outside of the cell
Allele is expressed IB because it is dominant
Allele 0: red blood cells will NOT produce an antigen (protein)
Allele is expressed i because it is recessive

7. Human Codominance Blood Types
Determining Blood types is necessary before you receive a blood transfusion because incompatible red blood cells clump together or clot causing death.
Your immune system or antibodies recognizes the red blood cells belonging to you. If cells with a different type of antigen enter your body your immune system will attack them

8. Multiple Alleles
The ______ different phenotype blood groups: A, B, O, & AB
Are produced by ______ different alleles: A, B, and O
FILL in your chart.
Which ones are homozygous?
Which ones are heterozygous?
four
Phenotype
All Genotypes Possible
Type A (Dominant)
IAIA (AA), IAi (AO)
Type B (Dominant)
IBIB (BB), IBi (BO)
Type AB (Codominant)
IAIB (AB)
Type O
(recessive)
ii (OO)
three

9. Will the following cause death?
Can a person with type A blood receive type O blood?
Can a person with type B blood receive type AB blood?

10. Multiple Alleles
Sample problems of Blood type crosses