(a) Describe the main stages of mitotic division.
(b) State four ways in which mitosis is important to living organisms.
Explanation
(a) Main stages of mitotic division:Prophase –
- Chromosomes appear as two threads/chromatids
- chromatids are long thin and/later become shorter and thicker; and joined together at the centromere; the nuclear memberane; and the nucleolus disappear
- spindle fibres form in the cytoplasm; with a pair of centrioles; one at each pole.
Metaphase:
- spindle formation is completed
- the chromosomes are arranged at the equator of the spindle
- attached by their centromeres; centromeres divide; and begin to move apart. Anaphase
- The paired chromatids are pulled apart/separated
- migrate/move towards opposite poles
- spindle fibres shorten; chromatids reach the poles.
Telophase –
- Fibres disappear, nuclear materials and nucleolus are formed
- bounded by nuclear membrane
- the cell constricts
- to form two daughter cells.
(b) Importance of mitosis:
- Promotes cell growth
- replacement/repair of damaged tissues
- basis of asexual/ vegetative reproduction
- produces genetically identical offspring
- which are identical to the parents
- maintains the diploid number of the chromosome of the cell.