Mitosis Mitosis - is the most common method of cell division.After mitosis, two daughter cells are an exact copy of the parent.The longest phase of mitosis - prophase it.During her spiralizuyutsya and thicken the chromosome, which is contained information about the cell.In the resting phase chromosomes found in the nucleus, but in prophase nucleoli and nuclear membrane are dissolved, and now the hereditary material is dispersed throughout the cytoplasm.Centrioles divergent poles of the cell to form a division spindle.
After prophase metaphase begins.During this period, the chromosomes are arranged so that their centromeres aligned exactly along the equator of the cell.By centromeres attached thread spindle.
During the next stage - anaphase centromeres are doubled.Chromatids that make up the chromosomes are separa
ted from each other and thread spindle, cutting, start to pull them toward the poles.
During telophase cytoplasm divides and the rest of the organelles.Chromosomes unwind and re-form the core and the longitudinal hauling the mother cell divides into two daughter.
doubling of genetic material occurs during interphase - the gap between the divisions when the cell is at rest.
Meiosis Meiosis - this division, during which the number of chromosomes is reduced by half.Meiotic division occurs in germ cells of plants and animals.Meiosis goes through two cycles, which, at first glance, is similar to mitosis, but there are significant differences.During prophase I, which in mitosis much longer than in meiosis, chromosomes join and exchange of genetic information among themselves.Meiotic anaphase I is characterized in that during it the centromere is not divided, and by means of spindle pole to the cell reaches only one of the homologous chromosomes.After the first division immediately begins the second resulting in the formation of four cells, each of which has a single set of chromosomes.It will double again after fertilization occurs.
Some of the simplest organisms, meiosis takes place in another way, lying only one cycle of division.
amitosis - a rare occurrence, usually occurs in aging, or doomed to death of the cell, which is usually an emergency vehicle.During amitosis not formed division spindle.The cell is divided by simple constriction, and hereditary material is distributed between daughter cells at random.