inheritance Background Codominance occurs when both alleles in the heterozygote express themselves fully Because both of the alleles are fully expressed both alleles are equally emphasized in the genotypic notation For example a codominant trait in humans is blood type The letters A and B that identify blood types refer to the two different carbohydrates that coat the surface of red blood cells If you have type A blood you have type A carbohydrate on your red blood cells Type B blood had type B carbohydrate Type AB has both carbohydrates and Type O has no carbohydrates These alleles are represented by an I and a superscript A or B to indicate whether the allele codes for type A or B blood See the chart below for the phenotypes and genotypes of the human blood groups Blood Groups Phenotypes A B AB O Genotypes IAIA or I i IBIB or IBI JAIB ii Question A woman with blood type AB marries a man with blood type O Is it possible for them to have children with the same blood type as either of the parents If no what are the possible blood types of their children Create a Punnett square to help explain your answer Create a Punnet square depicting what you believe to be your parents genotype for blood type in the space below Explain what information you used to determine each of your parents blood genotypes Explain how you can use this information to help maintain your personal health