Mitosis

Definition

noun, plural mitoses

The process where a single cell divides resulting in generally two identical cells, each containing the same number of chromosomes and genetic content as that of the original cell.


Supplement

Prior to this, the genetic material of the original (parent) cell has replicated during the S phase of the cell cycle so that when the cell enters mitosis it undergoes four major phases which culminates in the formation of two identical (daughter) cells:

1st phase: Prophase: formation of paired chromosomes, disappearance of nuclear membrane, appearance of the achromatic spindle, formation of polar bodies

2nd phase: Metaphase: arrangement of chromosomes in the equatorial plane. Chromosomes separate into exactly similar halves.

3rd phase: Anaphase: the two groups of daughter chromosomes separate and move along the fibres of the central spindle, each toward one of the asters, forming the diaster.

4th phase: Telophase: two daughter nuclei are formed, the cytoplasm divides, forming two complete daughter cells.

Originally, the term mitosis refers only to nuclear division unaccompanied by cytokinesis (which is the division of the cytoplasm), as in the case of some cells like certain fungi and in fertilized egg of many insects. As used now, mitosis used interchangeably with cell division.


Word origin: from Greek mitos, warp thread + –OSIS.
Related forms:
mitotic (adjective), mitotically (adverb).
Synonym:
karyokinesis.
Compare:
meiosis.
See also:
cell, cell division.


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