Genetic material (DNA) doubles in the S phase of interphase. <span><span>Chromosomes do not double in mitosis - they are already double as a result of the S phase</span></span>
Actively dividing eukaryote cells pass through a series of stages known collectively as the cell cycle: two gap phases (G1 and G2); an S (for synthesis) phase, in which the genetic material is duplicated; and an M phase, in which mitosis partitions the genetic material and the cell divides.
G1 phase.
