Mitosis

MITOSIS

The term mitosis was first used by W.Flemming(1882)

It is the process of cell division in which a cell divides into two daughter cells with same number of chromosomes as that of the parent cell. So it is also called as 'Equational' cell division.This occurs in somatic or vegetative cells of higher plants and all eukaryotes.

The mitosis includes two types of division

1) Karyokinesis 2) Cytokinesis

This includes 4 major stages

(1) Prophase (2) Metaphase (3) Anaphase (4) Telophase



1. PROPHASE

2. METAPHASE
 * This is the first stage of mitosis.
 * Chromosomal material are condensed to form compact chromosomes.
 * in this stage chromosomes has two chromatids.
 * the two chromatids are joined at a place called centromere.
 * The nucleolus disappears and later the nuclear envelope starts disintegrating.

3. ANAPHASE
 * During this phase, each chromosomes contain two chromatids become still more compact,short and align themselves in the equatorial plane or metaphase plate.
 * The nuclear envelope totally disappears.
 * The arrangement of the chromatids is haphazardly arranged at the equatorial plane.

4. TELOPHASE
 * This stage begins when the centromere of each chromosome splits into two.
 * This allows sister chromatids to separate and move towards opposite poles.
 * The migration of chromatids to opposite poles is achieved by the contraction of chromosomal fibers and certain other cytoplasmic activities.
 * In this stage of cell divison the shape of the chromatids is mostly v and u- shaped.


 * In this stage, chromosomes are assembled at the poles.
 * They begin to uncoil and then return to interphase condition.
 * The mitotic spindle degenerates.
 * Nuclear envelope reappears around both chromosomal sets.
 * Cell plate formation takes place producing two identical daughter cells.