CELL DIVISION
Cell division as such is a continuous process however for convenience it has been divided into four phases viz prophase metaphase anaphase and telophase cell division is mainly required for body growth and to cope up with wear and tear cells of the skin intestinal lining bone marrow etc are rapidly dividing cell whereas cells of liver divide very slowly in contrast cells of nervous tissue and skeletal and heart muscle totally lose their ability to divide when they are fully mature however repairs of such tissues may be done by replacing these cells by fibrous connective tissue the cell division phase can be subdivided into four subphases viz prophase metaphase anaphase telophase
interphase is the interval between each cell division i.e between the end of telophase of one cell division and beginning of prophase of the next division during this phase metabolism of cell is activated chromosomes become elongated and chromatin granules become visible each chromosome duplicates to form two chromatids attached at centromere
Prophase :: in this phase the thin tangled chromatin strands become shortened and thickened to form chromosomes each chromosome each chromosome has a centromere to which are attached four chromatids in meiosis two chromosome of homologeous pair come together as a unit and they mix in each other to the process called synapsis in mitosis the chromosome are independent and divide into two single stranded daughter chromosomes during the prophase nuclear membrane slowly disappears the two centrioles move to the opposite side and some fibrils link up to form the spindle nucleolus also disappear
metaphase : in this phase the chromosome start moving towards the centromere in mitosis one of the two single stranded daughter chromosomes move toward each centromere whereas in meiosis one of the each homologous pair moves apart i.e towards opposite centromeres
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