Cells divide through the process of mitosis in order to repair and replace old or damaged cells, to grow, and to develop multicellular organisms. Mitosis consists of prophase, metaphase, anaphase and telophase where the genetic material and cytoplasm are divided to form two identical daughter cells. The cell cycle, which is the life of a cell, includes interphase where the cell grows and duplicates its DNA in preparation for division, and M-phase where mitosis and cytokinesis occur. The cell cycle is tightly regulated by internal factors such as cyclins and cyclin-dependent kinases and external growth factors to ensure cells only divide when necessary.