We're going to call protein B that will be found on the membrane of the red blood cells. And the third allele basically means at the locus, we have a sequence of nucleotides that doesn't code for either one of these proteins. And so lowercase I is the allele that expresses neither protein A or protein B on the membrane of red blood cells. So we have phenotype A or protein A. We have phenotype protein B and we have a phenotype in which neither of the proteins are actually expressed. Now, remember, in diploid organisms, every single chromosome comes with a homologous pair.