Mitosis
The number of chromosomes in the parent and the daughter (Progeny) cells remain the same so it is also called as equational division.
Mitosis is divided into four stages they are :
prophase :
1. Prophase is the longest phase in mitosis.
2. Chromosomes condence become visible as long thin thread like structure.
3. Initiation of spindle fibres takes place, nucleolus disappears. Nuclear envelope breaks down.
4. In animal cell , the centrioles form asters.
5. Plant cells do not form asters.
Metaphse :
1. Chromosomes (two sister chromatids) are attached to the spindle fibres by kinetochore of the centromere.
2. The alignment of chromosome into compact group at the equator of the cell is known as metaphase plate.
Anaphase :
1. Each chromosome split simultaneously and two daughter chromatids begins to migrate towards two opposite poles of a cell.
2. Shortening of spindle fibre and longitudinal splitting of centromere creates a pull which divides of centromere into two halves.
Each half receive two chromatids (that is sister chromatids are separated).
4. A ubiquitine ligase is activated called as the
anaphase -promoting complex cyclosome (APC/C) Which is a cluster of proteins that induces the breaking down of cohesion proteins which leads to the separation of chromatids during mitosis.
Telophase :
1. Two sets of daughter chromosomes reach opposite poles of the cell, mitotic spindle disappears.
2. Two sets of daughter chromosomes reach opposite poles of the cell, mitotic spindle disappears.
3. Nucleolus and nuclear membranes reforms.
4. Now the chromosomes decondense.
Cytokinesis: In plant cells division of cytoplasm occurs by cell plate formation. In animal cells, fibril helps the generation of a contractile force.
This force draws the contractile ring inward forming a cleavage furrow in the cell surface dividing the cell into two.
