what is importance of Mitosis? It maintains the similarity of genetic material in all the cells of the body (2) It is a method of growth by addition of cells in multicellular organisms (3) It maintains similar chromosome number in all the cells of the body (4) All the above.
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Answer:
Mitosis
Mitosis constitutes a comparatively small portion of a complete cell cycle but it is one of the imperative parts of the cell cycle. German Physician and cell biologist “Walther Flemming” coined the term “mitosis” in the year 1882. He explained the process of how cells split and separate their chromosome.
The process of cell division that results in the formation of two new daughter cells is termed as Mitosis. The newly formed daughter cells are genetically identical to the parent cell and to each other. It plays a crucial role in a living organism’s life cycle. However, the level of significance may vary depending on the type of organism (multicellular or single-celled).
In unicellular organisms such as bacteria, mitosis helps in asexual reproduction as it produces an identical copy of the parent cell. Another example of the Eukaryotic unicellular organism is “Amoeba.” An amoeba uses cell division for the production of new individuals. In the case of multicellular organisms, mitosis helps in growth and repair by producing more number of identical cells. For example plants, animals depend on cell division for their growth by addition of new cells. It is also used for repairing the injured tissues or replacing the worn-out tissue by regenerating new cells.
Mitosis refers to the splitting of chromosomes in the eukaryotic cells during the cell division process. The parent cell divides into two daughter cells that are identical to the parent cell during the process of cell division. During the mitosis process, the cell’s nucleus along with the chromosome is divided to form two new daughter cell nuclei. The daughter nuclei inherit the same number of chromosomes as that of the parent nucleus.
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Prophase
In this phase the DNA supercoils, chromatin fibres become coiled and condense into chromosomes. The chromosomes consist of two chromatids connected at the centromere. The microtubule spindles fibres start forming at the opposite ends of the cell. The mitotic spindle is composed of microtubule proteins that slowly increase in length during the prophase which eventually initiate the cell division process by elongating it.
The pairs of centrioles (two pairs) move away from each other towards the poles during the microtubule lengthening process. Finally, the nuclear envelope disintegrates and the nucleus dissolves.
Late Prophase
Late prophase is also known as the prometaphase. The nuclear envelope dissolves. The microtubules composed of spindle fibres move from the pole to the centre of the cell (cells equator). Kinetochores attach themselves to specialized microtubules called kinetochore fibres.
Metaphase
In metaphase, the spindle entirely develops. The nuclear membrane dissolves completely. Polar fibres keep on extending from the poles to the centre of the cell. Chromosomes assemble and disassemble themselves and try to find the centromere of sister chromatids. The chromosomes arrange themselves in the metaphase plate at 90 degrees to the spindle poles. The polar fibres produce equal forces and push the centromere of chromosome thus holding the chromosomes together at the metaphase plate.
Anaphase
The pairs of centromeres present in the chromosome start to move away in this phase. The sister chromatids, paired chromosomes, separate and form a complete chromosome, also termed as daughter chromosomes. The daughter chromosomes start moving towards the poles in the opposite ends through the spindle apparatus.
Telophase
The polar fibres keep on lengthening. Nuclei forms at the opposite end. Nuclear envelopes start developing from the leftover pieces of the nuclear envelope of the parent cell and from the endomembrane system. Nucleoli start reappearing. Chromatin fibres of the chromosome unwind. At this point, the process of mitosis is almost complete and the genetic material of the parent cell is equally divided into two.
Cytokinesis
The division of the cell cytoplasm is termed as cytokinesis. It starts before the anaphase stage and ends just after telophase. Two genetically identical daughter cells are formed after the end of cytokinesis. The new daughter cells are identical diploid cells. Each cell contains a full set of chromosome.