What is the key to the recognition of codomiance? One version of a gene is dominant, while the other is recessive. This is called codominance. It occurs because an organism has both alleles, and each of them has a different phenotype. The phenotype of a heterozygote falls between those of its homozygotes.
Blood type AB is the most common example of codominance. Type AB is the most common example of codominance. The blood type AB is a heterozygote whose phenotype falls between the A and C blood groups. As a result, the blood type of a person is a mixture of traits that result from the dominance and recessive traits.
Two dominant alleles are required to produce the blood type AB phenotype. In addition, genotype IAIB produces H antigens containing galactose and N-acetyl-galactosamine. Codominance is observed in plants with two distinct color phenotypes such as red and white flowers. The two dominant alleles produce roughly equal amounts of protein.
Incomplete dominance is also recognized when a single allele is expressed over a heterozygote. This can be seen in many cases, such as in red-haired cows. In some instances, the alleles are expressed over both chromosomes. This type of inheritance is known as polygenic inheritance. If one parent is heterozygous for both alleles, the child will have the same phenotype.
Completion dominance is another type of inheritance. Here, each parent contributes different genes. Incomplete dominance refers to a combination of both the dominant and recessive genes. A pink flower, for example, would have both dominant and recessive alleles. Or a bird would be codominant for white or blue feathers. A heterozygote can inherit either type of inheritance.