Meiotic division

Mitosis and meiosis is part of the cell cycle and cover only 5-10% of the cell cycle. Large percentage of time in the cell cycle occurs at the interface. Interphase consists of periods of G1, S, and G2. In the G1 period in addition to the formation of these compounds to DNA replication, replication also occurs cytoplasmic organelles that cells grow larger, and then the cell enters the phase of the S period of DNA replication process. After DNA replication, cell growth (G2) to prepare all the needs for the separation of chromosomes, and then followed by a process of nuclear division (M) and cytoplasmic division (C). Further cell division results into new cell growth (G1).

Inexplicable factor of Mendel in the behavior of mitosis and meiosis bear a tremendous boost to perform genetic studies. New terms then appear. That appears first is given the name of the discipline itself genetics (genetics), and the default unit basis Mendel called genes (gene). Two homologous genes representing two alternate forms called allelomorf (allelomorphs) then shorted allela (alleles). Individuals who develop from a fertilized egg called a zygote (zygote), individuals homozygous (homozygote) is an individual who brings a pair of identical allela, and vice versa heterozygous (heterozygote) for individuals who bring a different pair of allela of specific genes. The total number of genes present in one individual, in other words all the genome called chromosome (genome). Meiosis is the process that produces haploid gametes from diploid cells undergo meiosis in two successive division, called meiosis I and meiosis II. Meiosis reduces or reduce the number of chromosomes in half. The resulting daughter cells are 4 cells, not 2 like cell mitosis. Two meiotic divisions held by only one chromosome duplication process, so the result is four daughter cells have only half the number of parent chromosomes. Reduction of the number of chromosomes occurs during meiosis I. In the event of a reduction in the two chromosomes in meiosis of diploid cells into each single unit, it gives individuals a single replica of each unit of heredity to haploid germ cells with which he begot
derivatives. Each phase in meiosis has its own characteristics. The characteristics of chromosome behavior in the form of a nearly equal mitotic division. Phases in meiosis are as follows:

Meiosis occurs only in the sexual reproduction phase or on the network nuftah. At meiosis, there is pairing of homologous chromosomes as well as a reduction in the number of parent chromosomes to daughter cells. In addition, meiosis occurs twice in a period of cell division, the division I (meiosis I) and second division (meiosis II). Meiosis I and meiosis II occurs in plant cells. Similarly, in animal cells occurs meiosis I and meiosis II. Both the meiotic divisions I and II, occur as phases of the mitotic division. Therefore, it is known the existence of prophase I, metaphase I, anaphase I, telophase I, prophase II, metaphase II, anaphase II, and telophase II. As a result of two processes of cell division, then in meiosis, a stem cell will produce four
sbaru, with each cell containing half the chromosome number of the chromosome number of stem cells.


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