The longest stage of the cell cycle is interphase/10%3A_Cell_Reproduction/10.02%3A_The_Cell_Cycle/10.2A%3A_Interphase). Interphase is the phase of the cell cycle in which a typical cell spends most of its life. It is divided into three stages: G1 (first gap), S (synthesis of new DNA), and G2 (second gap). During interphase, the cell grows and carries out biochemical functions, such as protein synthesis, in the G1 phase. In the S phase, DNA is duplicated into two sister chromatids, and centrosomes, which give rise to the mitotic spindle, are also replicated. In the G2 phase, energy is replenished, new proteins are synthesized, the cytoskeleton is dismantled, and additional growth occurs/10%3A_Cell_Reproduction/10.02%3A_The_Cell_Cycle/10.2A%3A_Interphase). The synthesis phase of interphase takes the longest because of the complexity of the genetic material being duplicated/10%3A_Cell_Reproduction/10.02%3A_The_Cell_Cycle/10.2A%3A_Interphase).