The professor explained that the case at hand is a simple example of X-inactivation mosaicism, with the inclusion of a white spotting gene. He clarified that all female mammals possess two X-chromosomes. In cats, one gene for fur color is situated on the X chromosome. As a result, any female cat will exhibit mosaic expression of all the genes located on the X chromosome, implying that half of them would express one version of the gene (like black fur) while the other half would express the other version of the gene (like orange fur). The inactivation process follows a random pattern. Although this pattern is conspicuous in the orange/black mosaicism case, it holds true for other genes on the X chromosome that have two distinct versions or alleles.