Mention the stages of Mitosis with the help of diagrams. Explain the changes that takes place in Prophase.
A. Mitosis is a method of cell division, in which the nucleus divides into two daughter nuclei each containing the same number of chromosomes as the parent nucleus mito¬sis takes place in all body cells which retains same number of chromosomes.
Different stages of mitosis :
- Prophase 2) Metaphase 3) Anaphase 4) Telophase
1) Prophase : In this phase chromosome contract, spiral and become even in light microscope and nucleoli becomes smaller. Chromosome split lengthwise to form chromatids connected by centromeres. Nuclear membrane breaks down. Centrosome containing rod like centrioles, divide and form ends of spindle.
2) Metaphase: Chromosomes move to spindle equator, centromeres attached to spindle fibres.
3) Anaphase : Centromeres split separating the chromatids. Spindle fibres attached to centromeres contract, pulling chromatids towards poles.
4) Telophase: Chromatids elongate, become invisible; nuclear membranes form round daughter nuclei. Cell membrane pinches into form daughter cells or new cell wall material becomes laid down across spindle equator (plants). Nucleus divides into two and division of cytoplasm starts.