What is mitosis? Mitosis is a process that involves separation of the chromosomes from the eukaryotic cell. The chromosomes are divided into two parts in its nucleus cells. The process of mitosis takes place immediately after the process of cytokinosis. Cytokinosis is a process that involves division of nuclei, organelles, cytoplasm and cell membrane into two parts. The process of mitosis and cytokinosis is known as mitotic phase.
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The process of mitosis takes place in every organism but the process differs from one specie to specie. The process takes place only in the eukaryotic cells. In animals the ‘open’ mitosis takes place and the nuclear covering breaks before the chromosomes separate. The tiny organisms such as fungi, bacteria, yeast undergo a ‘closed’ mitosis process and hence the chromosomes are divided by a process known as binary process. They tiny organisms consist of prokaryotic cells and they do not consist of nucleus and hence the chromosomes are divided by a process called binary fission.
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The process of mitosis takes place very quickly. The process of mitosis comprises of several stages which include prophase, interphase, promatephase, metaphase, anaphase and telophase. During the process of mitosis, the chromatids contract and they get attached to the fibers. These cells are divided during the phase of cytokinosis and hence two daughter cells are formed.
The stage of interphase is relatively shorter and it consists of three stages i.e., first gap, synthesis, and second gap. During these phases, the cells grow and produce proteins. During the protophase stage, the nucleus migrates into the center of the cell and phragmosome is produced. In the prophase stage, chromatin which is in the form of bundled coil is produced. The chromatin that is produced usually contracts in this cycle. In the prometaphase, the membrane of the nucleus separates from the cells and the microtubules enter the nucleus of the cells.
During the phase of metaphase, the centromosomes that are located between the cells drag away the chromosomes through centromeres. During the anaphase, the kinetochore is attached to the microtubules. Telophase, is a reverse process of prophase and promeataphase. During this phase, the microtubules begin to grow.
The process of mitosis is significant and the cells that are produced in the body receive chromosomes and hence the cells grow in this way.
The process of mitosis takes place during the following cycles:
- Growth of cells: When the chromosomes are produced in the body, the number of cells in the body increases.
- Replacement of cells: The cells that are damaged in the body should be destroyed and new cells should be formed. In this way, the body can function smoothly. By the process of mitosis the cells can be replaced in the body. The cells present in the skin and digestive tract are constantly replaced.
- Regeneration: Some parts of the body can be regenerated when the process of mitosis takes place. In this way new cells are produced through the process of regeneration.
- Asexual reproduction: Some organisms reproduce asexually when the process of mitosis takes place.
Probably the first thing that comes to the mind when you hear the word cell is the question – “What is Mitosis?” The mother cell divides itself into two exactly similar daughter cells. This is the method of their reproduction. The daughter cells can further divide to create two more cells and the process is simply endless. However, the mother cell just cannot divide without any preparation. They need to go through a certain process for the same.
Each human cell has two sets of 23 chromosomes. When the mother cell is ready to divide, it makes a copy of the two sets. This means for a short interval of time it has four sets each having 23 chromosomes. When the mother cell divides, each daughter cell gets a pair. This cell division is technically known as Mitosis.
Thus, Mitosis is the process of nuclear cell division where the nucleus divides to produce two identical chromosomes.
The Phases of Mitosis
There are four phases of Mitosis.
The very first stage of Mitosis is called Prophase. In normal conditions, the chromosomes are equally spread across the nucleus of the cell. However, with the advent of Prophase, they start contracting into the central part of the nucleus and form a dense ball. The DNA molecules also interact with the agents that assist in the reproduction. These agents include protein and enzymes. The contracted chromosomes are called mitotic chromosomes. A spindle apparatus is formed which separates or pull apart the duplicate chromosomes in the later stages.
The second stage of the process is known as Metaphase. The chromosomes that are to be divided start aligning in a particular direction in the central part of the cell. They also interact and coordinate with the Spindle apparatus as formed in the first stage.
The third and probably the most important stage of the process is called Anaphase and this is where the separation of chromosomes actually occur. The spindle apparatus pulls the identical chromosomes into two separate identical units. These units would later on become the nucleus of two daughter cells. The daughter cells are identical not only to each other but to the mother cell as well.
The last and final stage of the process that is exactly opposite to the Prophase is called Telophase. The word itself means end. The spindly apparatus vanishes and the chromosomes are surrounded by a newly formed membrane that is also known as the nuclear envelope. The cell divides into two separate ones.
Before the prophase, cell prepares itself for the reproduction. The stage is called Interphase. The cell produces cytoplasmic organelles and proteins and grows in size. The duplicate chromosomes are also produced in this stage. In plant cells, the Prophase is also followed by Preprophase.
With the commencement of Telophase, a separate process called Cytokinesis is also initiated. It is not a part of the Mitosis process but is extremely important for the reproduction.