In this article we will discuss virtually the iv phases of mitosis with suitable diagram and as well learn about its significance.
The mitosis is a part of somatic cell division which includes the sectionalization of the nucleus (called mitosis or karyokinesis) and the segmentation of the cytoplasm (called cytokinesis). Strasburger (1875), a German botanist, was the first to work out the details of mitosis. Mitosis can be studied best in the root tip and shoot tip of several plants. Only the most favourable material is the apices of onion roots.
In mitosis, the metabolic nucleus passes through a complicated organization of changes in the form of four different stages, viz., prophase, metaphase, anaphase and telophase. Some important aspects of all these stages are discussed beneath.
i. Prophase (Gr. pro, before):
i. Information technology is the commencement and the longest phase in the mitotic cell partition.
2. Chromosomes become visible in the nucleus every bit curt, thick, helically coiled threads (Fig. 305A).
3. Each chromosome splits into two chromatids (Fig. 305B, C) joined at the centromere.
iv. Nuclear membrane starts dissolving.
5. Nucleolus also starts dissolving and disappearing.
6. Prophase changes into adjacent stage called metaphase.
4. Chromosomes become shorter and thicker.
5. Chromosomes arrange themselves in the centre or on the equator of spindle.
six. At the end of metaphase, two chromatids of each chromosome also start separating.
ii. Metaphase (Gr. meta, between):
1. Nuclear membrane disintegrates and disappears completely (Fig. 306).
2. Nucleolus disintegrates and disappears completely.
3. Spindle fibres start appearing and these fibres get attached to chromosomes at centromeres.
four. Chromosomes go shorter and thicker.
5. Chromosomes arrange themselves in the heart or on the equator of spindle.
half-dozen. At the stop of metaphase, two chromatids of each chromosome too starting time separating.
seven. Metaphase changes into the next stage chosen anaphase.
iii. Anaphase (Gr. ana, back):
1. Chromatids separate from each other at centromere and called daughter chromosomes (Fig. 307).
ii. Daughter chromosomes move to the reverse poles of the spindle.
3. Girl chromosomes appear ‘V’, ‘U’ or J-shaped during their movement towards poles.
4. Anaphase changes into the next phase called telophase.
four. Telophase (Gr. telo, stop):
1. Daughter chromosomes are now at the end of the spindle, i.e., nowadays on two opposite poles (Fig. 308A).
2. Nuclear membrane reforms around each grouping of daughter chromosomes (Fig. 308B).
three. Nucleolus reforms (Fig. 308C).
iv. 2 nuclei are thus organised, one at each pole of the parent cell.
v. Chromosomes begin to loose their compact construction.
6. Spindle fibres disappear gradually.
7. Thus formed 2 girl nuclei are exactly like to the parent nucleus.
Significance of Mitosis:
ane. Mitosis results in the formation of two daughter cells identical with that of the parental cell.
2. Past this process, DNA, the chief component of chromosomes, is distributed equally among the 2 newly formed nuclei.
3. Both the daughter cells formed later mitosis are identical and have the aforementioned genetic constitution, qualitatively besides as quantitatively, every bit the parent prison cell.
iv. The number of chromosomes remains the same from ane generation to another generation.
5. Resulted girl cells have the aforementioned characters as were present in the parent cell.
vi. The characters of the plants grown past vegetative reproduction may exist preserved for a long period.
Which Phase of Mitosis is Shown in the Diagram