Topic Mitosis As A Type Of Cells Division
Table of Contents
- Meaning Of Mitosis
- Stages Of Mitosis
- Importance Or Role Of Mitosis
- Life Processes Involved In Mitosis
What Is Mitosis?
Mitosis is a cell or nuclear division following the duplication of chromosomes, whereby each daughter cell or nucleus has exactly the same chromosome content as the parent. In other words, mitosis is a cell division in which daughter cells have the same number of chromosomes as the parent cell.
Mitosis takes place in somatic cells, i.e., body cells that are not involved in the production of gametes. Mitosis takes place during an organism’s growth, development and asexual reproduction. In plants, mitosis takes place in the terminal bud of the shoot at the tip of the roots and shoots. In animals, mitosis occurs at growth centres which are everywhere.
Mitosis produces diploid cells. In other words, the number of chromosomes in each somatic cell of an organism is called the diploid number (2n).
Stages of Mitosis
There are five stages or phases of mitosis. These are:
1. Interphase: This is the latent or resting stage of the cell. At this stage, the cell has normal appearance of non-dividing cell condition. Chromosomes are too thread like clear visibility.
2. Prophase: The prophase is divided into two: Early and late prophase. During early prophase, the chromosomes become visible as they contract and nucleolus shrinks. Entrioles are formed at the opposite sides of the nucleus. Spindle fibres starts to form during the late prophase, the chromosomes become shorter and fatter. Each is seen to consist of a pair of chromatids joined at the centromere and nucleus disappears. Prophase ends with the breakdown of nuclear membrane.
3. Metaphase: Metaphase also exists in early and late forms. During early metaphase, the equator of the spindle and at late metaphase, the chromatids draw apart at the centromere region.
(Note that the chromatids of each chromosome are orientated towards the opposite poles of the spindle).
4. Anaphase: Anaphase also exists in early and late forms. During early anaphase, the chromatids part company and migrate to opposite poles of the cell while during late anaphase, the chromosomes reach their destination, i.e., toward the poles.
5. Telophase: Telophase stages is equally divided into early and late forms. During the early telophase, the cell starts to constrict across the middle. During late telophase, the constriction continues. The nuclear membrane and nucleolus reform in each daughter cell. Spindle apparatus degenerates. The chromosomes eventually regain their thread like form and the cell returns to resting condition (i.e interphase).
(Note that the daughter cells have precisely the same chromosome constitution as the original parent cell).
Importance or Role of Mitosis
1. Growth, development or specialisation takes place as a result of mitosis.
2. Repair of cells are possible through mitosis.
3. Mitosis ensures exact copy of DNA or sum total inherited factors or genes are transmitted to the daughter cell or it ensures consistency of DNA configuration.
4. Mitosis also is the basis for asexual reproduction. E.g. Binary and multiple fission of Amoeba.
Life Processes Involved in Mitosis
Life examples of mitotic process include:
i. Formation of new cells in the malphighian layer of the skin.
ii. Production of red blood and white blood cells in the bone marrow.
iii. Cell division in liver.
iv. Cell division in meristem or tip of root or in cambium.
v. Binary fission.
vi. Growth in spermatogenesis.
vii. Repair or healing of wound.