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Subject - cell biology
Meiosis (also known as reductional division) is a form of cell division in which the number of chromosomes is reduced by half and the maternal and paternal genetic material is newly combined. Beginning with a diploid cell, the process of meiosis forms a haploid cell. Therefore, in contrast to mitosis, this division does not produce genetically identical cells. This type of cell division occurs in gametogenesis, i.e. the formation of sperm in the male organism and egg cells in the female.
Meiosis is preceded by a duplication of the chromosomes so that each chromosome consists of two at the beginning. There are two steps to the division. In the first meiotic division, the pairs of homologous chromosomes are separated and the original maternal and paternal chromosomes are randomly distributed to the daughter cells, which results in a new combination of the parental genetic material. Afterward, in the second meiotic division, the chromatids are separated as in mitosis. The prophase of the first meiotic division (Prophase I) is a far more complicated process than the mitotic prophase. It is thus subdivided into several stages. Prophase I may also involve the exchange of individual chromosome segments through crossing over.
Recommended Learning Units
BiochemistryBiological FundamentalsCell Cycle
Cell reproduction is based on the principle of cell division. In order to divide a cell into two identical daughter cells, all of the genetic material and all cell components must be duplicated. Animated illustrations demonstrate the cell cycle responsible for this, as well as illustrating cell division by mitosis and meiosis.