When cells are duplicated, there is transfer of DNA or genetic information from the parent cell to the daughter cells. So for this transfer to be made possible and to ensure equal transfer of this genetic information to the daughter cells, DNA has to be replicated. If there is duplication of cell without the splitting of DNA, one of the daughter cells wouldn’t have a DNA and this tends to make the whole concept of cell division ineffective and unnecessary.
Immediately DNA is replicated, the cell divides into two daughter cells with each having an identical copy of the original DNA. If a cell undergoing division has not fully copied all of its chromosomes or perhaps there has been damage to the DNA, the cell will remain in the S phase of division until all of the chromosomes have been properly copied. If the DNA still isn’t replicated, the cell will experience a programmed cell death.