And so we form these two X cells, XL one and XL two, which are abnormal. They have anuploid. One of these cells lacks a copy of chromosome 21, but the other cell has not one, but two copies of chromosome 21. And so now if we take a sperm cell, so this is our sperm cell that also has let's suppose we have a normal sperm cell and that means we have a normal amount of chromosome number one. We only have one. When this sperm cell, normal sperm cell combines with Xcel number two, we're going to form a Zygote that has the following genotype distribution for chromosome 21.