How do phenotypes appear in codominance?

(kō-dŏm'ə-nəns) n. A state in which both alleles of a gene pair in a heterozygote are fully expressed, with neither one being dominant or recessive to the other. An excellent way to illustrate codominance is through the explanation of blood types. Our blood types are A, B, AB, and O. We won't be discussing Rh (D) factor at this time. A can be either AA or AO, B can be either BB or BO, AB is AB, and O is always OO. The AB type demonstrates codominance because its genotype (AB) and phenotype (AB) are identical, and OO is not codominant because this O is recessive to the other types.

In codominance, both alleles in a heterozygous individual are expressed fully and simultaneously, resulting in the appearance of both phenotypes. This means that neither allele is dominant over the other. As a result, the heterozygous individual displays a phenotype that exhibits characteristics of both alleles equally.