What Are The Functions Of Mitosis In Multicellular Eukaryotic Organisms Such As Plants And Animals

What is Mitosis?

In 1887, the German anatomy biologist, Water Fleming, coined the term mitosis which comes from the Greek language and translates to "wrap thread" from mitos and "act or procedure" from the osis part of mitosis. This term was based on the warped thread advent of the chromatin of the cell nucleus in the start stages of mitosis. Now, what is mitosis as a process? Mitosis is the process in jail cell division by which the nucleus of the cell divides (in a multiple stage), giving ascension to ii identical daughter cells.

Mitosis happens in all eukaryotic cells (plants, animals, and fungi). It is the process of prison cell renewal and growth in a plant, animal or fungus. It is continuously occurring throughout our bodies; it is fifty-fifty happening while yous are reading this. Cells continuously dice; this process is termed apoptosis (programmed cell decease). For you to stay live and fully functional, these cells need to be continuously replaced. Mitosis is crucial to this process. Mitosis is the reason we tin grow, heal wounds, and replace damaged cells.

Mitosis is too important in organisms which reproduce asexually: this is the only style that these cells tin can reproduce. This is the one key process that sustains populations of asexual organisms. Mitosis allows for some organisms to main alternating life stages (asexual and sexual, such equally fungi).

The primal to mitosis occurring is the presence of a nucleus. Therefore, organisms without nuclei (prokaryotes) miss out on this impressive process.

Before Mitosis

Earlier mitosis begins, the chromosomes in the nucleus of the cell undergo replication. This is because mitosis produces two girl cells identical to the parent prison cell; then the number of chromosomes in the parent and girl cells must be the same. Mitosis produces two diploid cells from one diploid prison cell. Thus, chromosome numbers must double before mitosis occurs. Continue in listen; diploid refers to the number of chromosomes in a cell: haploid cells have 1 prepare of chromosomes (n), as is establish in a gamete (sexual activity jail cell), whereas diploid cells take 2 sets of chromosomes (2n).

Overview of Mitosis

During mitosis, all chromosomes separate into chromatids (the two halves of a chromosome). These chromatids are and so separated in space earlier cell partition, to form the chromatic makeup of each daughter cell. Because there are double the number of diploid chromosomes in the parent cell (two Ten 2n = 4n), when these chromosomes are separated into their chromatids and divide into ii groups, each group will accept the same number of chromatids, and therefore chromosomes, as each other and as the parent cell. The limerick of these chromosomes will also be identical. One time the chromosomes are separated in space, jail cell sectionalization occurs to produce two daughter cells. Thus, mitosis uses chromosome replication to produce two identical diploid girl cells, which are genetically identical to the diploid parent cell. This way all your cells take identical DNA composition.

The Phases of Mitosis

The process of mitosis can be mind boggling to grasp fully; here nosotros will try to work through it systematically. Get-go off, mitosis can be separate into v phases: Prophase, prometaphase, metaphase, anaphase and telophase. Some textbooks vary in the number of phases. In some instances they do away with prometaphase and just keep the four fundamental phases.

What exactly happens in each phase of mitosis in animals may differ to what happens in plants. Yet, all cells undergoing mitosis will in one fashion or another undergo each of the to a higher place mentioned phases.

You will need to familiarize yourself with the post-obit terms to fully understand the phases of mitosis explained beneath:

Jail cell furrow/cleavage furrow	Image Source: Flickr	The indentation found in the jail cell membrane of a recently divided animal cell
Cell plate		The synthesized division of a constitute jail cell laid across the metaphase plate. This later forms the middle lamella
Centriole	Image Source: Wikimedia Eatables	An organelle associated with spindle fiber production, located in the centrosome. These are only found in animal cells
Centrosome		The part of the cytoplasm which contains the centrioles
Microtubules		Hollow protein tubes which form spindle fibers (among other things)
Tubulin	Image Source: Wikimedia Eatables	The protein which makes upwards microtubules
Kinetochore microtubules	Image Source: Wikimedia Eatables	The microtubules which attach the centrosome to the kinetochore
Kinetochore		Plates of poly peptide at a chromosome'south centromere, to which spindle fibers attach during mitosis
Centromere	Image Source: Wikimedia Commons	The bespeak of constriction of a chromosome
Cohesin	Paradigm Source: Wikimedia Commons	The poly peptide which binds 2 sister chromatids
Cytokinesis	Prototype Source: Wikimedia Commons	Sectionalization of the cytoplasm into two equal parts
Equatorial aeroplane/metaphase plate	Image Source: Wikibooks.org	The midline of the cell along which chromosomes align during metaphase
Interphase	Image Source: Wikimedia Commons	The period between mitosis occurrences; the catamenia betwixt one telophase and the next prophase
Centre lamella	Image Source: Wikimedia Eatables	The jail cell structure between side by side plant cell walls
Nuclear envelope	Epitome Source: Wikimedia Commons	The double membrane which encloses the nucleus
Nucleolus		The center of rRNA production inside the nucleus
Sister chromatids	Image Source: Wikimedia Commons	The 2 identical chromatids which form a chromosome
Spindle fibers	Image Source: Wikimedia Eatables	A bundle of microtubules running from one pole of the cell to another, along which chromosomes move

Now that the definitions are out of the mode let us get started on the nitty gritty of this process.

ane. Prophase

This is the longest phase of mitosis. Numerous important events occur in this phase, the centrioles migrate, the spindle fibers are organized, the nuclear envelope disintegrates, the nucleolus also disintegrates, and the chromatin fibers condense (Figure one).

Figure 1: The major events occurring in the prophase stage Image Source: Wikimedia Eatables

Prophase in animate being cells begins with the migration of two pairs of centrioles from merely outside the nucleus, in the centrosome, to polar ends of the cell. Once at polar ends of the cell, the centrioles promote the movement of microtubules from the cytoplasm into the spindle fibers. Plant and fungi cells do not have centrioles; therefore, they skip this step.

While this is occurring, the nuclear envelope and nucleolus disintegrate, releasing the chromatin within. The chromatin condenses, and chromosomes become visible. The two chromatids making up each chromosome are identical and are known equally sister chromatids. These are held together by cohesin.

Retrieve of this phase this way, every role of the cell that is involved in mitosis changes to prepare for the total mitotic process. For case, at the end of mitosis the daughter cells need equal amounts of identical DNA, and so in that location has to be a way of making sure that the right contents go to the right prison cell. In other words, there has to be an insurance mechanism for making certain that ane cell does not end upwardly with ii copies of the one chromosome while the other cell ends up with nothing copies of this chromosome. This is achieved through the hard piece of work of spindle fibers which pull the contents of the one girl cell to the one side while the other "one-half" is pulled towards the opposite terminate. This way, chromosomes never get lost and become to the incorrect end. In brusque, things drift to their rightful corners.

The presence of the nuclear envelope limits how far chromosomes, in item, can go. And so earlier the cell tin consider pulling things apart and duplicating the contents, this barrier need to be removed somehow. This is why the nuclear envelope disintegrates.

If you lot follow the logic higher up it should be obvious why the other events occur. Read over the explanation presented below of the unabridged process and and then go.

2. Prometaphase

Prometaphase is an intermediary stage between prophase and metaphase, here the cell is further prepared for metaphase (effigy 2).

Effigy 2: The events of the prometaphase stage. Prototype Source: Wikimedia Commons

The spindle fibers attach to the kinetochore of each chromosome, at opposite sides of the centromere. Each sis chromatid is fastened to its spindle fibers. These spindle fibers are comprised of kinetochore microtubules. The chromosomes migrate to the equatorial plane (or metaphase plate), which is perpendicular to the spindle fibers.

Here the same logic as above applies; it is all most making certain one chromatid ends upward in ane cell.

3. Metaphase

Metaphase refers to the alignment of the chromosomes at the equatorial plate following prometaphase.

Figure 3: The alignment of chromosomes at metaphase. Prototype Source: Wikimedia Eatables

Each centromere is aligned with the equatorial plate while the chromosome artillery extend towards the poles. Each sister chromatid (even so joined at this point) is on a different side of the equatorial plate (effigy 3).

iv. Anaphase

The Anaphase stage is the shortest stage of mitosis.

Effigy four: Sister chromatids are pulled towards opposite poles of the parent cell. Prototype Source: Wikimedia Eatables

During this stage, disjunction occurs, and migration of sister chromatids away from each other to the poles of the cell occurs, leading to the formation of daughter chromosomes.

Molecular motors use ATP to shorten the spindle fibers attached to each sister chromatid. In so doing, the chromosomes are split up into two genetically identical sister chromatids, known as daughter chromosomes from this point. This event is known as disjunction. As the spindle fibers shorten further, the daughter chromosomes are drawn further apart until grouped at contrary ends of the jail cell.

There is now a diploid number of chromosomes at each pole.

five. Telophase

Telophase is the final phase of mitosis. Afterward anaphase, two diploid sets of chromosomes are located at each pole of the jail cell. Cytokinesis then occurs to split up the jail cell into two identical daughter cells.

Figure 5: The parental cell constricts to form two daughter cells identical to each other and the parent prison cell. Image Source: Wikimedia Commons

In animate being cells, the cytoplasm is constricted to the point that the cell is divided in two. This results in a cell furrow. In found cells, a prison cell plate is laid at the position of the equatorial airplane. This later becomes the eye lamella of the plant cell.

Following this, chromosomes are packed to become chromatin, a nucleolus reforms, and a nuclear envelope forms around the chromatin and nucleolus. The spindle fibers disappear, and the jail cell enters interphase.

Figure 6: A simplified overview of mitosis. Paradigm Source: Wikimedia Commons

Now that nosotros have explored all the unlike stages go back reread and endeavor to reason each event. This will provide you with the ability to reply whatever questions most each and every ane of these stages.

Why is Mitosis Of import?

Mitosis is important for 3 master reasons: development and growth jail cell replacement and asexual reproduction.

i. Evolution and growth

After meiosis has produced a gamete, and this has fused with another gamete to course an embryo, the embryo grows using mitosis. This growth continues throughout an organism'due south life, in plants, animals, and fungi. In this way, the original chromosomal set is preserved.

two. Cell replacement

This occurs when the original cell is damaged or wounded. New cells are created to replace those that were damaged. Examples of this are the healing of a cutting or a broken bone. When old cells die, new ones replace them to ensure continuing functionality.

3. Asexual reproduction

Single-celled organisms and sure multicellular organisms use mitosis for asexual reproduction. This includes reproduction by fragmentation, as in the instance of planaria, and reproduction by budding, every bit in the case of sea anemones. Many plants reproduce using mitosis.

How is Mitosis Different from Meiosis?

First, we need to empathize what meiosis is. Meiosis is the replication of cells that results in each daughter nucleus containing half of the parent prison cell's chromosomes. Meiosis is used primarily for the production of gametes, which are incorporated in sexual reproduction. Thus, the main difference between mitosis and meiosis is that mitosis produces somatic (torso) cells, which can go on to become role of any actual tissue, whereas meiosis merely produces germ (sex) cells. Organisms which reproduce asexually cannot undergo meiosis, whereas all eukaryotic organisms undergo mitosis.

Mitosis and meiosis are similar in that both can simply occur in eukaryotic cells. This is because prokaryotic cells practice not contain a nucleus within which to begin the processes of mitosis and meiosis. Instead, prokaryotes replicate themselves using binary fission. Both mitosis and meiosis begin with DNA replication in the parent jail cell to create four sets of chromosomes: in mitosis, these sets are carve up to form two diploid daughter cells, while in meiosis, these sets are separate to course iv haploid daughter cells. This is because cells undergo only i partition in mitosis, whereas they undergo two divisions in meiosis.

The tabular array below summarizes the similarities and differences between mitosis and meiosis.

Mitosis	Meiosis
Similarities
Can only occur in eukaryotes
Dna replication occurs first
Production of daughter cells based on parent cell'due south genetic fabric
Means of cell replication in plants, animals, and fungi
Differences
Starts as diploid; ends as diploid	Starts as diploid; ends as haploid
Used for growth/healing/asexual reproduction	Used for sexual reproduction
1 nuclear segmentation	2 nuclear divisions
v phases	8 phases
Daughter prison cell identical to parent cell	Daughter jail cell not identical to parent cell
Results in 2 daughter cells	Results in 4 daughter cells
Produces somatic cells	Produces germ cells
Occurs in asexual and sexual organisms	Occurs only in sexual organisms

Wrapping Up Biology and Mitosis

We now know that mitosis is the process of asexual prison cell replication that is responsible for an organism'south development and growth, its cell replacement, and also, in sure organisms, asexual reproduction. Mitosis is, therefore, an integral role of eukaryotic functioning. Mitosis differs from meiosis in that meiosis is the product of gametes, or sex cells, which will allow for genetic recombination in sexual organisms. Still, without mitosis, the embryos formed will never grow to become organisms. Mitosis is preceded by DNA replication, to course 2 diploid sets of chromosomes. Mitosis has five phases. The first stage is prophase, where the chromatic material is released from the nucleus, and centromeres migrate to the poles of the cell. Prophase is followed by prometaphase, where the chromosomes drift to align at the equatorial plane of the cell. The third stage is metaphase, where the chromosomes are fully aligned at the equatorial plane. Metaphase is followed by anaphase, wherein the sister chromatids forming each chromosome are pulled autonomously to assemble at the poles of the cell; and telophase, where cytokinesis forms two identical daughter cells, genetically identical to the parent cell. Following this, the cell enters interphase, the phase between mitosis events.

Mitosis has given eukaryotic organisms the ability to regenerate cells as necessary without reducing the chromosome set while meiosis has allowed the possibility of genetic recombination. Both are vital for the prevalence and continued survival of eukaryotic organisms.

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