It is important for DNA to be copied before cell division, is because after cell division you will result in two identical daughter cells, but only from one parent cell that we are talking about. In order to result in two daughter cells that contains the same information as the parent cell, we have to duplicate the DNA before dividing the parent cell into two daughter cell, to ensure each daughter cell will have one copy of the parent's DNA after dividing. Therefore, a parent cell will have (46 chromosomes), and making two daughter cells (EACH with 46 chromosomes).