Interphase is longest part of the cell cycle and is subdivided into three growth phases: G1, S and G2 phases. The G1 stage stands for "GAP 1", the S for "Synthesis" and the G2 for “GAP 2”. During G1 the cell grows, but not from a size standpoint. This growth occurs at the biochemical level where the cell begins to accumulate building blocks in the form of proteins and energy sources in the form of carbohydrates. The S phase is marked by DNA growth. DNA is replicated to form identical pairs of chromosomes called sister chromatids. *Note: after replication cells are still diploid (2N) but in humans would now contain 92 total chromosomes (46 original + 46 exact copies). The S phase also marks the appearance of the centrosome, an organelle that will orchestrate the movement of the sister chromatids to that new cell. The G2 phase marks another surge in biochemical growth that replenishes used up proteins and energy from the previous phases. During G2 the cytoskeleton will start to be broken apart in preparation for cell division. Some cells will enter a G0 phase following the cell cycle which represents an inactive state which length varies by cell type, with some cells remaining in G0 permanently.