Mitosis
Mitosis is the process, in the cell cycle, by which a cell duplicates into two genetically identical daughter cells. In mitosis, chromosomes in the cell nucleus are separated into two identical sets of chromosomes, each in its own nucleus. In general, mitosis is followed immediately by cytokinesis, which divides the cytoplasm, organelles, and cell membrane, and later karyokinesis, which divides the nucleus, dividing the cell into two new cells containing roughly equal shares of these cellular components. Mitosis and cytokinesis together define the
mitotic phase of the cell cycle—the division of the mother cell into two daughter cells, genetically identical to each other and to their parent cell. This accounts for approximately 20% of the cell cycle. Mitosis occurs only in eukaryotic cells and the process varies in different groups. For example, animals undergo an "open" mitosis, where the nuclear envelope breaks down before the chromosomes separate, while fungi such as
Aspergillus nidulans and
Saccharomyces cerevisiae undergo a "closed" mitosis, where chromosomes divide within an intact cell nucleus.