Explanation Of Mitosis
Mitosis is the process of cell division. It is a stage of the cell cycle in which newly formed DNA is separated and two new cells with the same number and type of chromosomes as the parent nucleus are formed. Except for germ cells, most eukaryotic cells divide in such a way that the ploidy or number of chromosomes remains constant.
During the growth and development, an organism's body is filled with cells through the process of mitosis. Throughout its life, mitosis replaces worn out and old cells with new cells. The mitotic division is a form of reproduction that adds new individuals to the population of single-celled eukaryotes. Mitosis' primary goal is to ensure that each daughter cell formed has a complete and perfect set of chromosomes. This does not function properly if the cells have an excess or a lack of chromosomes. Features
Features of Mitosis
In each mitotic cell division cycle of mitosis, two daughter cells are formed from a mother cell.
This means that each nucleus divides once during each cell cycle.
In size, shape, and chromosome complement, the daughter cells are similar to their mothers' cells.
The chromosome number in the daughter and mother cells is the same, which is known as equational or homotypic division.
Mitosis occurs in plants' somatic organs as well. This can be found at the stem tip, root tip, and leaf base. Mitosis is the process by which plants grow their vegetative parts.
The entire mitosis process is made up of only one equational or homotypic division.
There is no recombination or segregation during the mitosis stage.
Stages of Mitosis
The cell cycle is the period during which one cycle of a cell's division is completed. The cell cycle is divided into two phases is Interphase and Mitotic phase
The interphase is when DNA is synthesized, and the mitotic phase is when nuclear division occurs. The time required to complete the cell cycle varies by species.
1. Interphase
A cell spends a period of its growth in interphase before entering mitosis. When in interphase, it goes through the following phases:
G1 Phase: This is the period preceding DNA synthesis.
S Phase: This is the phase in which DNA synthesis occurs.
G2 Phase: The period between the end of DNA synthesis and the start of prophase.
2. Mitosis phase
During the mitotic phase, the replicated DNA is separated into two daughter nuclei. It occurs in the absence of recombination. This means that the daughter nuclei will have the same chromosome combination as the parent nucleus.
Further, there are four sub-stages under the mitotic phase and they are-
a. Prophase
The prophase starts after the G2 stage of interphase. The chromosome appears as a thin, uncoiled thread in the early prophase stage. The chromosome becomes coiled and short, as well as more distinct, during mid-prophase. The chromosome will appear thicker, shorter, and more conspicuous in late prophase, as well as double longitudinally.
b. Metaphase
The phase following prophase is known as metaphase. The spindle tubes form during this stage, and the chromosome is oriented in the centre at the equatorial plate. A spindle tube is present that connects the chromosome to the centromere. The chromosomes are visible clearly during metaphase. The sister chromatids of each chromosome are joined at the centromere, but their arms remain free.
c. Anaphase
Anaphase begins with the separation of the sister chromatids. These sister chromatids become the daughter nuclei's chromosomes. The fibres that are attached to the kinetochores of each chromosome then pull the chromosomes towards the pole. Each chromosome's centromere leads at the edge, with the arms following behind it.
d. Telophase
During the telophase, the chromosomes that cluster at the two poles begin to coalesce into an undifferentiated mass as the nuclear envelope forms around it. The nucleolus, Golgi bodies, and ER complex, which had vanished during prophase, begin to reappear.
Functions of Mitosis
Mitosis, or cell division, helps an organism grow from a baby to an adult.
Mitosis also performs the functions of growth and repair.
Significance of Mitosis
It is in charge of a body’s growth and development.
It keeps the number of chromosomes constant in all body cells of an organism.
Mitosis is required for asexual reproduction, vegetative propagation in plants, and is also in charge of tissue repair and regeneration.
Mitosis contributes to genome purity by preventing recombination and crossing over.
It is responsible the repair and regeneration of old and damaged cells in animals, like gut epithelium and blood cells.
FAQs on Mitosis
1. Is mitosis the same in plant cells and animal cells?
Plants and animals have the same interphase, prophase, metaphase, anaphase, and telophase. Unlike animal cells, which go through cytokinesis, plant cells create a new cell plate in the middle, which results in the formation of new cells. When the division process is completed, the cell plate transforms into a cell wall.
2. What happens when there is an abnormality during mitosis?
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3. Mention the differences between sister chromatids and homologous chromosomes?
Homologous chromosomes are those that have the same genes but different alleles for those genes. One chromosome comes from the father and the other from the mother in a homologous pair (in humans). Sister chromatids are identical and contain the same genes. When DNA is replicated before a cell enters mitosis, sister chromatids form.
4. Is Cytokinesis a part of mitosis stages?
No, cytokinesis is not a mitotic stage, but it is a component of the mitotic phase. This leads to the formation of two daughter cells. Mitosis is only concerned with the nucleus, whereas cytokinesis divides the cells after mitosis is completed.
5. Do every cell in the body go through the growth and repair process?
No, cytokinesis is not a mitotic stage, but it is a component of the mitotic phase. This lead to the formation of two daughter cells. Mitosis is only concerned with the nucleus, whereas cytokinesis divides the cells after mitosis is completed.
6. Do all the cells go Through Growth and Repair?
Some cells like the muscle cells and the nerve cells cannot regrow or get repaired once they form fully. When they are mature it is important to take care of them.
7. How does Mitosis help in Repair?
When we get a cut, the cells that are present around the edge of the cut undergo mitosis that helps to repair the cut. The same happens when there is a broken bone.
8. Is Cytokinesis a Stage of Mitosis?
No, cytokinesis is not a stage of mitosis but it is a part of the mitotic phase. This results in two daughter cells. Mitosis is related only to the nucleus but cytokinesis divides the cells after the completion of mitosis.
9. Is the Mitosis Phase the Same in Plant and Animal Cells?
Yes, the interphase, prophase, metaphase, anaphase, and telophase are the same in plants and animals. However, whereas the animal cells go through cytokinesis, in the plant cells, a new cell plate is created in the middle, and this creates new cells. Once the division is over, the cell plate changes into a cell wall.
10. What if There is an Abnormality During Mitosis?
An abnormality in the mitosis stage alters the DNA and this results in many genetic disorders.
