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Cell division
Cell division is the process where a parent cell divides into two or more daughter cells. There are two main types of cell division: mitosis and meiosis. Mitosis is a vegetative division where each daughter cell is genetically identical to the parent cell. It involves the separation of duplicated chromosomes into two identical sets during nuclear division followed by cytokinesis which divides the cell cytoplasm and organelles. Meiosis results in gamete cells with half the number of chromosomes and involves one round of DNA replication followed by two cell divisions. Both mitosis and meiosis occur in sexually reproducing organisms at some point in their life cycle.
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Cell division
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- 2. Cell division-is theprocess by which a parent cell divides into two or more daughter cells. Cell division usually occurs as part of a larger cell cycle. In eukaryotes, there are two distinct type of cell division: a vegetative division, whereby each daughter cell is genetically identical to the parent cell (mitosis),
- 3. and a reductivecell division, whereby the number of chromosomes in the daughter cells is reduced by half, to produce haploid gametes (meiosis) Meiosis results in four haploid daughter cells by undergoing one round of DNA replication followed by two divisions: homologous chromosomes are separated in the first division, and sister chromatids are separated in the second division.
- 4. Both of thesecell division cycles are in sexually reproducing organisms at some point in their life cycle, and both are believed to be present in the last eukaryotic common ancestor Prokaryotes also undergo a vegetative cell division known as binary fission, where their genetic material is segregated equally into two daughter cells. All cell divisions, regardless of organism, are preceded by a single round of DNA replication.
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- 9. Mitosis is theprocess by which a cell, which has previously replicated each of its chromosomes, separates the chromosomes in its cell nucleus into two identical sets of chromosomes, each set in its own new nucleus. It is a form of nuclear division.
- 10. It is generallyfollowed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles, andcell membrane into two cells containing roughly equal shares of these cellular components. Mitosis and cytokinesis together define the mitotic (M) 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 10% of the cell cycle.
- 11. Mitosis occurs onlyin eukaryotic cells and the process varies in different species. For example, animals undergo an "open" mitosis, where the nuclear envelope breaks down before the chromosomes separate, while fungi such asAspergillus nidulans and Saccharomyces cerevisiae (yeast) undergo a "closed" mitosis, where chromosomes divide within an intact cell nucleus. Prokaryotic cells, which lack a nucleus, divide by a process called binary fission.