Mitosis definition

During the mitotic phase, a cell splits into two genetically similar daughter cells, which leads to cell duplication and reproduction.

Both daughter cells retain the same number of chromosomes.
Chromosome condensation, segregation, as well as cytoplasmic division occur during the brief mitotic phase.
In somatic cells, a process called mitosis is used to multiply the number of cells during plant and animal embryogenesis and blastogenesis.
All animals and plants go through mitosis, which is very similar in all of them.

Purpose of Mitosis

Both cell division and cell reproduction depend on the process of mitosis. The following list includes some of the main meanings or purposes:

Continuous mitosis increases the cell population, allowing the organism to develop from a single cell into a sophisticated living being.
Mitosis continually replaces many cells in the body, including skin cells and red blood cells. Humans create 5 109 cells via the process of mitosis per day.
Similar to how starfish regenerate their body structures, mitosis also plays a role in these processes.
Mitosis is the process of asexual reproduction in many organisms.

Stages of mitosis

The S phase of interphase precedes the cell cycle stage of mitosis, which is followed or accompanied by cytokinesis most often. Prior to the start of mitosis, chromosomal replication and protein synthesis necessary for spindle fibre production take place.

According to the start of one set of operations and the start of another, mitosis is split into the following stages.

1.Interphase

The cell replicates its DNA during the interphase phase of the cell cycle to get ready for the M phase (mitotic phase).
Interphase is often referred to as the most active phase of the cell cycle, since it sees an increase in cell metabolism.
Throughout this period, a number of metabolic alterations that may be further broken down into three categories take place.

G1-phase or Pre-DNA synthesis phase

It is the cell cycle’s longest phase, and the M phase from the previous cell cycle comes next.
Since no DNA synthesis occurs during this phase, it is also known as the “resting phase.”
However, various cell organelles enlarge during the G1 phase, and the cell produces several varieties of RNA and proteins quickly.
Significant activities during this phase include the transcription of three different RNA types; the synthesis of regulatory proteins; DNA-synthesising enzymes; tubulin proteins; and other mitotic equipment.

S-phase or DNA Synthesis phase

Nuclear DNA replication and the production of histone proteins both take place during the S-phase. Any stage of the cell cycle may result in cytoplasmic DNA replication.
As a result, each chromosome contains two DNA molecules and a duplicate set of genes at the conclusion of the S phase.
This stage lasts between six and ten hours.

G2-phase or Post DNA synthesis phase

Second gap phase or resting phase of the interphase are terms used to describe the G2 phase.

The production of RNA and proteins needed by the cell continues throughout this stage.

The huge energy expenditure required for cell division causes the cell to accumulate ATP in the G2 phase.

The cell enters the division, or M-phase, of the cell cycle at the conclusion of this phase.

2. Prophase

The initial stage of mitosis, known as prophase, is characterised by the emergence of chromosomes that condense into thin threads.
The cytoplasm becomes more refractile, viscous, and pale during prophase, while the cell takes on a spheroid shape.
Two coiled filaments known as chromatids, produced as a consequence of DNA replication in the S phase, make up the chromosome in the prophase.
The chromatids shorten and thicken during prophase, and a unique DNA-rich area known as the centromere holds two sister chromatids of each chromosome together.
Similar to this, the chromosomes move toward the nuclear envelope, leaving the nucleus’s interior region unoccupied.
While this is happening, two pairs of centrioles that are encircled by microtubules that radiate in all directions move to the cell’s opposing poles.
Last but not least, prophase is terminated as the nucleolus progressively breaks down.
However, the nuclear envelope does not break down during mitosis in several primitive groups of plants and animals.
3. Prometaphase

The opening of the nuclear envelope triggers prometaphase by allowing spindle fibres to interact with the chromosomes.
The chromosomes are now being forcefully spun and oscillating back and forth between the spindle poles because their centromeres are capturing the ends of microtubules, and they are being pulled by the captured microtubules.
The sister chromatids are kept on the metaphase plate by the end of prometaphase when they are connected to the spindle fibres on their opposing ends.
4. Metaphase

The chromosomes are the thinnest and shortest during metaphase.
The sister chromatids’ centromeres create a metaphase plate with their arms still pointing in the direction of the poles in the plane of the equator.
A chromosome’s two chromatids repel one another while the microtubules stay in place and are under stress.

Anaphase

Each chromosome splits synchronously into its sister chromatids, known as daughter chromosomes, which separate at the centromere, signalling the start of the anaphase.
An increase in cytosolic Ca2+ during prophase is what splits each centromere.
Due to the shortening of the microtubules, chromatids shift toward the pole during anaphase.
The centromeres stay forward throughout their migration to the pole, giving the chromosomes their typical U, V, or J form.
Chromosomes are supported as they migrate toward the pole by expanding interzonal fibers.
To transport chromosomes to the poles, 30 ATPs are needed.

Telophase

The telophase starts when the daughter chromosomes have finished migrating to the poles.
The prophase’s actions take place in reverse order during the telophase.
Each set of chromosomes is surrounded by a nuclear envelope that reassembles to create two daughter nuclei.
Telophase is characterised by processes including the loss of the mitotic apparatus, a decrease in cytoplasmic viscosity, and RNA production.
At the conclusion of telophase, the nucleolus resurfaces and the chromosomes regain their long, thin, stretched shape.

Cytokinesis

Cytokinesis is the division of the cytoplasm, while mitosis is the process that produces the development of two distinct daughter cells.
Anaphase is often the start of cytokinesis, which continues through telophase and into interphase.
Animals undergo constriction and furrow creation during cytokinesis.
In animal cells, constriction of the plasma membrane during anaphase is the first indication of cleavage.
Constriction generally takes place at a right angle to the long axis of the mitotic spindle apparatus, in the plane of the metaphase plate.
From the outer to the inside, the constriction deepens until a cell eventually splits into two daughter cells.
However, since solid cell walls prevent constriction, cytokinesis in plants is accomplished by the development of cell plates.
The phragmoplast, which eventually gives rise to the cell plate in plants, is formed by the arrangement of golgi apparatus on the equator.

Applications of Mitosis

Many laboratory-based molecular biology and biotechnology procedures use mitosis. Mitosis is often used for things like:

1,Cloning

In biotechnology, the process of cloning is used to create identical copies of DNA or cellular components.
Mitosis is utilised in cloning to multiply the number of organisms, which are subsequently employed in a variety of scientific tests, including fingerprinting.

Tissue culture

Tissue culture is the method of culturing cells or tissues exterior to an organism’s body in a liquid, semi-solid, or solid growth medium.
The process of mitosis, in which a cell divides to generate several tissues, serves as the foundation for tissue culture.
Additionally, tissue culture in different species might result in organ culture.

Stem cell regeneration

A collection of cells called stem cells may be stimulated to develop into certain types of cells in the body.
To regenerate and repair sick or damaged tissues in individuals, stem cells may go through mitosis.

References

Verma PS and Agarwal VK (3005). Cell Biology, Genetics, Molecular Biology, Evolution, and Ecology. Multicolored Edition.
Rastogi SC (2006). Cell and Molecular Biology. Second Edition. New Age International.
http://www.authorstream.com/Presentation/aSGuest108184-1131832-application-of-mitosis/
https://www.siyavula.com/read/science/grade-10-lifesciences/cell-division/03-cell-division-03

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