In genetics, alleles are half or more than half of the genes that go through a mutational process these two genes are located on the same location on a chromosome. A phenotype is the actual genetic characteristics that can be observed. This is opposed to the genotype which is the actual genetic make-up of a person or other organism.
When both of the alleles are able to be seen in the observable phenotype, this is when codominance is occurring. In blood, some of the alleles are dominant over the other genes. Some of them are co-dominant and others may be recessive. The main situation in codominance includes the alleles as well as the place where it is taking place which is in the phenotype.
