Define codominance in genetics.

Codominance refers to a situation in genetics where both alleles in a heterozygote are fully and independently expressed in the phenotype. This means that when an organism carries two different alleles for a trait, both alleles contribute to the individual’s appearance without blending or one overshadowing the other.

For example, in some cases of flower color in certain plants, if one allele codes for red flowers and the other for white flowers, the presence of both alleles may result in flowers that display both colors simultaneously, leading to a phenotype where both traits are visible. This distinct expression is what characterizes codominance, as opposed to situations where only one allele's effect is seen or where traits blend into an intermediate phenotype.

Understanding codominance is crucial in genetics because it highlights the complexity of inheritance patterns beyond simple dominant-recessive relationships, showcasing the diversity of genetic expression in the natural world.