There are two major types of cell division -- mitosis and meiosis. In addition to mitosis, the process of cytokinesis is involved in the division of cells. In plants, the cells produced through these two processes make up the body, which is made up of the roots, stem, leaves and parts of the flower. The process of meiosis is the mechanism behind sexual reproduction in animals and fungi.
Mitosis -- the process in which the nucleus of a cell divides -- is the first main stage or type of cell division. It can be broken down into four separate phases: prophase, metaphase, anaphase and telophase. Meiosis -- the second stage of cell division -- involves two cell divisions that produce four cells. Meiosis is different from mitosis in that all offspring differ genetically from others and have unique combinations of genes. In animals, meiosis produces gametes or specialized egg and sperm cells. In other organisms such as plants and fungi, meiosis produces spores.
Mitosis is the first stage of cell division. During prophase, chromatins condense to form chromosomes, fibers called mitotic spindles form at the poles of the cell, and sets of duplicated chromosomes called chromatids are brought together at the centromere. During metaphase, the mitotic spindles affix to the centromeres of the chromosomes. These chromosomes also assemble along the equator of the cell. During anaphase, the two sets of chromatids part at the centromere. One set moves toward a pole and the other identical set of chromosomes moves towards the other pole. In telophase, new membranes form around the daughter nuclei. The chromosomes and mitotic spindles disperse and are no longer visible under the microscope.
Cytokinesis is the second stage of cell division. During cytokinesis, a fibrous ring located around the center of the cell contracts and pinches the cell into two daughter cells. Each daughter cell contains a nucleus and a set of chromosomes. The two daughter cells are genetically identical to the parent cell with the exception of size. The two daughter cells are said to be clones of the parent.
There are two divisions of meiosis: the nuclear and cytoplasmic divisions. Similar to mitosis, each division includes a prophase, metaphase, anaphase and telophase. During prophase, two homologous pairs of chromosomes lie side by side while genetic material is exchanged. Chromatids are cut by enzymes and sections are switched and fused together which leads to more genetic variation among offspring. During metaphase, tetrads line up along the center of the cell and spindle fibers attach to the homologous chromosomes. During anaphase, the homologous chromosomes separate and move to opposite poles. Sister centromeres move to opposite poles as well. Each chromosome is duplicated and the nuclear envelope reappears.
