Mitosis:

This term was introduced by Flaming. This phase is called Equational division because number of chromosomes remains same as parent cells. It results in the formation of two daughter cells with same number of chromosomes as that of parents cell.

Further sub-phases of mitosis are explained below:

Prophase:

  • Chromosomes condense as thin threads.
  • Two centriols of centrosome move apart to opposite poles and some rays start arising from them, called Aster rays. These aster rays are linked by long fibres called Spindle fibres.
  • Nuclear membrane start disappearing.

Metaphase:

  • Nuclear membrane and nucleolus both completely disappears.
  • Spindle fibres are fully visible in an orderly manner.
  •  Chromosomes are attached to spindle fibres through their central kinetochores.
  • These chromosomes are arranged in a single vertical line on equatorial plate of spindle fibres.

 Anaphase:    

Here, the kinetochores of chromosomes are separated from the equatorial plate of spindle      fibres and chromatids start moving towards opposite poles.

Telophase:

  • Here, chromatids fully moved to their final opposite poles.
  • Chromosomes become less condensed.
  • Nuclear membrane and nucleolus reappears.
  • Spindle fibres disappears.

Cytokinasis:  It occurs finally to make new daughter cells in order to copy entire cytoplasm of cells and its equal distribution in two new daughter cells. Cell replication takes several forms, it occurs by cell plate formation in plant cells and in animal cells it occurs by furrowing:

  • Cell Plates are structures that grow in plant cells. Plant cells form a cell plate (cellulose wall) that separates the two new cells.
  • Cleavage Furrows are depressions in animal cells. In animal cells, a cleavage furrow on the outer surface indicates that two new cells are forming.
Related Keywords
11    PMT    Biology    Cell Cycle and Cell Division    Mitosis