Interphase is a phase of the cell cycle, defined only by the absence of cell division. Cells during interphase may or may not be growing. At any given time, even in an area of rapid cell division such as the tip of a plant root, 90 per cent of cells are in interphase. Some cells, such as nerve cells, can stay in interphase for decades. The cell grows and replicates its DNA and centrioles. There are 3 parts of interphase: G1 (growth 1 in which the cell creates organelles and begins metabolism), S phase (DNA synthesis in which the chromosomes of the cell are copied) and G2 (growth 2 in which the cell grows in preparation for cell division).