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

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

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 http://www.ccs.k12.in.us/chsteachers/Amayhew/Biology%20Notes/beyond%20dominance%20notes_files/image004.jpg

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

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

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

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

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

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?

Multiple Alleles Sample problems of Blood type crosses