Cell Cycle & Cell Division - Amitosis

Description:

Amitosis is also called direct or incipient cell division. It is the simplest type of cell division in which there is no synthesis of spindle. The chromatin fibres do not condense in amitosis. Nuclear membrane does not disappear during division.

Occurrence of Amitosis

• Found in certain prokaryotes like bacteria and cyanobacteria.
• Found in yeast.
• Some special eukaryotic cell types perform amitosis like cartilage cells, foetal membrane cells, endosperm cells of seeds.
• Amitosis can also occur in diseased cells and old tissues.

Amitosis Mechanism

It is comprised of two steps −

• Karyokinesis −

  • Involves division of nucleus.
  • Nucleus develops a constriction at the center and becomes dumbell shaped.
  • Constriction deepens and divides nucleus into two.

• Cytokinesis −

  • Involves division of cytoplasm.
  • Plasma membrane develops a constriction along nuclear constriction.
  • It deepens centripetally and finally divides the cell into two cells.

Amitosis – Drawbacks

• Causes unequal distribution of chromosomes.
• Can lead to abnormalities in metabolism and reproduction.