The nucleus of a cell only divides once during mitosis, which occurs only in eurkayotic cells. Mitosis is the process in the cell cycle that separates the duplicate chromosomes and nucleus of a dividing cell.
Mitosis is followed by cytokinesis, which is the final act of dividing the cytoplasm, organelles and cell membrane. Mitosis and cytokinesis together define the mitotic phase of the cell cycle. Mitosis consists of five distinct phases: prophase, prometaphase, metaphase, anaphase and telophase. Each of these phases involves characteristic steps in the process of chromosome alignment and separation. The physical processes involved in mitosis are called karyokinesis.