In other words, two alleles make up one gene. If two cordovan alleles are present, one from the queen and one from the drone, then the bee will exhibit the cordovan characteristic. Having two copies of the same allele at the same locus is commonly referred to as being homozygous for that particular gene. If the queen or the worker is heterozygous for the cordovan gene, meaning they have one wild type allele and one cordovan allele at the same locus, then the cordovan characteristic will not be expressed. However, a heterozygous queen is a carrier of the cordovan allele.
Drones exhibit the cordovan characteristic with only a single cordovan allele.
It is possible for drones to express the cordovan characteristic with a single cordovan allele because drones are haploid, meaning they possess only 16 chromosomes, while diploid workers and queens possess 32 chromosomes. It should be noted that the cordovan gene can be expressed in both dark and light races of bees. Naturally, the lighter the wild type within the race, the lighter the offspring will be once the cordovan gene is inserted. Dark races, with the addition of the cordovan gene, may appear black at first glance, but upon close examination, one will find that they are in fact a tarnished copper color. As stated previously, the cordovan gene alters the pigmentation of the exoskeleton, by eliminating black pigment.