But as the S phase proceeds, we basically use the cell machinery to replicate our DNA molecule, the chromosomes. So each one of the 46 individual chromosomes in human cells are replicated. And we produce the following two chromosomes, the original as well as the replicated. And we join these two chromosomes by using special proteins at a region known as the centromere found in this center location. Now, once we actually replicate the individual chromosomes, these individual chromosomes are now known as chromatids. So at this point, the cell basically contains 46 original chromatids and 46 replicative chromatids to make a combined total of 92 chromatids.