Describe different phasess of mytosis and mention its significance
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Answer:
Mitosis is a process of cell division, whereby a single cell divides into two genetically identical daughter cells. The five stage of mitosis are interphase, prophase, metaphase, anaphase and telophase.
Interphase
Almost 80 percent of a cell's lifespan is spent in the interphase stage of mitosis. During this stage, no division takes place, but the cell undergoes a period of growth and prepares itself for division. Cells contain many proteins and structures called organelles that must replicate in preparation for doubling. The DNA of the cell duplicates during this phase, creating two copies of each strand of DNA called a chromosome. A chromosome is a DNA molecule that carries all or part of the hereditary information of an organism.
Not all scientists class interphase as a stage of mitosis because it is not an active stage. However, this preparatory stage is essential before any actual cell division takes place.
Prophase
After the preparatory stage of interphase, prophase is considered to be the first true stage of the mitotic process.
During early prophase, the cell begins breaking down some structures and creating others, preparing for the division of chromosomes. The duplicated chromosomes from interphase condense, meaning they become compacted and tightly wound. The nuclear envelope breaks down, and an apparatus known as a mitotic spindle forms on the edges of the dividing cell. The spindle is made up of strong proteins called microtubules, which are part of the cell's "skeleton" and drive the division of the cell through elongation. The spindle gradually lengthens during prophase. Its role is to organize the chromosomes and move them around during mitosis.
Metaphase
At the very start of the metaphase stage, the pairs of condensed chromosomes line up along the equator of the elongated cell. Because they are condensed, they can move more easily without becoming tangled.
During metaphase, the nuclear membrane disappears completely. In animal cells, the two pairs of centrioles align at opposite poles of the cell, and polar fibers continue to extend from the poles to the center of the cell.
In rare cases, the cell does not stop division, and mistakes are made during mitosis. This can result in DNA changes, which can potentially lead to genetic disorder
Anaphase
During anaphase, the sister chromatids are drawn to opposite poles (ends) of the elongated cell. The protein "glue" that holds them together breaks down to let them move apart. This means duplicate copies of the cell's DNA end up on either side of the cell and are ready to divide completely. Each sister chromatid is now its own "full" chromosome. They are now called daughter chromosomes. At this stage the microtubules get shorter, which lets the process of cell separation begin.
Telophase
In the telophase stage, cell division is almost complete. The nuclear envelope, which had previously broken down to allow the microtubules to access and recruit the chromosomes to the equator of the dividing cell, reforms as two new nuclear envelopes around the separated sister chromatids.