Final answer:
DNA is synthesized before mitosis in cell division during the S phase of interphase.
Step-by-step explanation:
In cell division, DNA is synthesized before mitosis so it can form a complex with the enzyme MAP kinase, which activates the expression of proteins that initiate cell division. DNA synthesis occurs during the S phase of interphase, which precedes mitosis. During the S phase, the cell replicates its DNA so that each new daughter cell will receive a complete set of chromosomes.