As Baby Scorpions Grow Larger Which Process Occurs in Their Body (Somatic) Cells
What is Mitosis?
In 1887, the German beefcake biologist, H2o Fleming, coined the term mitosis which comes from the Greek language and translates to "wrap thread" from mitos and "deed or process" from the osis part of mitosis. This term was based on the warped thread advent of the chromatin of the cell nucleus in the first stages of mitosis. Now, what is mitosis as a procedure? Mitosis is the process in jail cell division by which the nucleus of the cell divides (in a multiple stage), giving rise to 2 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, beast or fungus. Information technology is continuously occurring throughout our bodies; information technology is even happening while you are reading this. Cells continuously die; this process is termed apoptosis (programmed cell death). For y'all to stay alive and fully functional, these cells need to be continuously replaced. Mitosis is crucial to this procedure. Mitosis is the reason we tin can grow, heal wounds, and replace damaged cells.
Mitosis is also important in organisms which reproduce asexually: this is the only way that these cells tin can reproduce. This is the one key process that sustains populations of asexual organisms. Mitosis allows for some organisms to principal alternating life stages (asexual and sexual, such as fungi).
The key to mitosis occurring is the presence of a nucleus. Therefore, organisms without nuclei (prokaryotes) miss out on this impressive procedure.
Before Mitosis
Earlier mitosis begins, the chromosomes in the nucleus of the cell undergo replication. This is because mitosis produces 2 girl cells identical to the parent cell; so 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. Keep in mind; diploid refers to the number of chromosomes in a jail cell: haploid cells have one set up of chromosomes (n), as is found in a gamete (sex cell), whereas diploid cells have ii sets of chromosomes (2n).
Overview of Mitosis
During mitosis, all chromosomes divide into chromatids (the two halves of a chromosome). These chromatids are so separated in space earlier cell sectionalization, to form the chromatic makeup of each daughter cell. Because at that place are double the number of diploid chromosomes in the parent cell (two X 2n = 4n), when these chromosomes are separated into their chromatids and split into two groups, each grouping will have the same number of chromatids, and therefore chromosomes, as each other and as the parent cell. The composition of these chromosomes will as well be identical. Once the chromosomes are separated in space, jail cell division occurs to produce ii daughter cells. Thus, mitosis uses chromosome replication to produce two identical diploid daughter cells, which are genetically identical to the diploid parent cell. This mode all your cells have identical Deoxyribonucleic acid composition.
The Phases of Mitosis
The procedure of mitosis tin exist mind boggling to grasp fully; here we volition attempt to piece of work through it systematically. First off, mitosis can be split into five phases: Prophase, prometaphase, metaphase, anaphase and telophase. Some textbooks vary in the number of phases. In some instances they practice away with prometaphase and just keep the 4 fundamental phases.
What exactly happens in each phase of mitosis in animals may differ to what happens in plants. Nonetheless, all cells undergoing mitosis will in ane way or another undergo each of the to a higher place mentioned phases.
You lot volition need to familiarize yourself with the following terms to fully understand the phases of mitosis explained below:
| Cell furrow/cleavage furrow |  | The indentation found in the cell membrane of a recently divided animal prison cell |
| Jail cell plate | The synthesized sectionalization of a plant cell laid beyond the metaphase plate. This later forms the middle lamella | |
| Centriole |  | An organelle associated with spindle cobweb 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 grade spindle fibers (among other things) | |
| Tubulin |  | The protein which makes upwards microtubules |
| Kinetochore microtubules |  | The microtubules which attach the centrosome to the kinetochore |
| Kinetochore | Plates of protein at a chromosome's centromere, to which spindle fibers attach during mitosis | |
| Centromere |  | The point of constriction of a chromosome |
| Cohesin |  | The protein which binds two sister chromatids |
| Cytokinesis |  | Division of the cytoplasm into two equal parts |
| Equatorial airplane/metaphase plate |  | The midline of the cell forth which chromosomes marshal during metaphase |
| Interphase |  | The menstruum betwixt mitosis occurrences; the period between i telophase and the next prophase |
| Middle lamella |  | The cell structure betwixt side by side constitute cell walls |
| Nuclear envelope |  | The double membrane which encloses the nucleus |
| Nucleolus | The center of rRNA production within the nucleus | |
| Sister chromatids |  | The two identical chromatids which grade a chromosome |
| Spindle fibers | | A bundle of microtubules running from one pole of the jail cell to another, along which chromosomes move |
Now that the definitions are out of the way allow us get started on the nitty gritty of this process.
1. Prophase
This is the longest stage of mitosis. Numerous of import events occur in this phase, the centrioles migrate, the spindle fibers are organized, the nuclear envelope disintegrates, the nucleolus too disintegrates, and the chromatin fibers condense (Figure one).
Prophase in animate being cells begins with the migration of ii pairs of centrioles from just outside the nucleus, in the centrosome, to polar ends of the cell. Once at polar ends of the cell, the centrioles promote the move of microtubules from the cytoplasm into the spindle fibers. Found and fungi cells do not take centrioles; therefore, they skip this footstep.
While this is occurring, the nuclear envelope and nucleolus disintegrate, releasing the chromatin inside. The chromatin condenses, and chromosomes become visible. The two chromatids making up each chromosome are identical and are known as sis chromatids. These are held together by cohesin.
Think of this phase this way, every part of the cell that is involved in mitosis changes to set for the full mitotic process. For example, at the finish of mitosis the daughter cells need equal amounts of identical DNA, so there has to be a fashion of making sure that the right contents go to the right cell. In other words, there has to be an insurance mechanism for making sure that i cell does not finish upwards with two copies of the one chromosome while the other cell ends up with zero copies of this chromosome. This is accomplished through the hard piece of work of spindle fibers which pull the contents of the one daughter jail cell to the 1 side while the other "one-half" is pulled towards the reverse end. This way, chromosomes never get lost and get to the wrong end. In brusque, things migrate to their rightful corners.
The presence of the nuclear envelope limits how far chromosomes, in particular, can become. And so before the cell can consider pulling things apart and duplicating the contents, this barrier demand to be removed somehow. This is why the nuclear envelope disintegrates.
If you follow the logic above it should exist obvious why the other events occur. Read over the explanation presented below of the unabridged process and then go.
2. Prometaphase
Prometaphase is an intermediary stage between prophase and metaphase, hither the cell is further prepared for metaphase (figure 2).
The spindle fibers attach to the kinetochore of each chromosome, at contrary sides of the centromere. Each sister chromatid is attached to its spindle fibers. These spindle fibers are comprised of kinetochore microtubules. The chromosomes drift to the equatorial airplane (or metaphase plate), which is perpendicular to the spindle fibers.
Here the same logic as above applies; information technology is all near making certain one chromatid ends upward in one cell.
3. Metaphase
Metaphase refers to the alignment of the chromosomes at the equatorial plate following prometaphase.
Each centromere is aligned with the equatorial plate while the chromosome arms extend towards the poles. Each sis chromatid (still joined at this point) is on a different side of the equatorial plate (figure 3).
four. Anaphase
The Anaphase phase is the shortest stage of mitosis.
During this phase, disjunction occurs, and migration of sister chromatids abroad from each other to the poles of the cell occurs, leading to the germination of daughter chromosomes.
Molecular motors employ ATP to shorten the spindle fibers attached to each sister chromatid. In so doing, the chromosomes are split into ii 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 autonomously until grouped at contrary ends of the cell.
There is at present a diploid number of chromosomes at each pole.
5. Telophase
Telophase is the concluding phase of mitosis. Afterward anaphase, ii diploid sets of chromosomes are located at each pole of the cell. Cytokinesis then occurs to split the cell into 2 identical daughter cells.
In creature cells, the cytoplasm is constricted to the point that the prison cell is divided in two. This results in a cell furrow. In plant cells, a prison cell plate is laid at the position of the equatorial plane. This later becomes the middle lamella of the constitute prison cell.
Post-obit 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 cell enters interphase.
Now that nosotros have explored all the dissimilar stages go dorsum reread and endeavor to reason each event. This will provide you with the ability to answer whatsoever questions nearly each and every one of these stages.
Why is Mitosis Important?
Mitosis is of import for three main reasons: development and growth cell replacement and asexual reproduction.
1. Development and growth
After meiosis has produced a gamete, and this has fused with another gamete to form an embryo, the embryo grows using mitosis. This growth continues throughout an organism's life, in plants, animals, and fungi. In this fashion, the original chromosomal set up is preserved.
2. Cell replacement
This occurs when the original cell is damaged or wounded. New cells are created to supervene upon those that were damaged. Examples of this are the healing of a cut or a cleaved os. When erstwhile cells die, new ones replace them to ensure continuing functionality.
3. Asexual reproduction
Single-celled organisms and certain multicellular organisms use mitosis for asexual reproduction. This includes reproduction by fragmentation, as in the example of planaria, and reproduction past budding, as in the case of sea anemones. Many plants reproduce using mitosis.
How is Mitosis Different from Meiosis?
First, nosotros demand to understand what meiosis is. Meiosis is the replication of cells that results in each daughter nucleus containing half of the parent cell'south chromosomes. Meiosis is used primarily for the product of gametes, which are incorporated in sexual reproduction. Thus, the main difference between mitosis and meiosis is that mitosis produces somatic (body) cells, which can keep to become office of whatsoever bodily tissue, whereas meiosis just 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 just 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 brainstorm with DNA replication in the parent cell to create four sets of chromosomes: in mitosis, these sets are split to form two diploid daughter cells, while in meiosis, these sets are divide to form four haploid girl cells. This is because cells undergo only one division in mitosis, whereas they undergo two divisions in meiosis.
The table beneath summarizes the similarities and differences betwixt mitosis and meiosis.
Mitosis | Meiosis |
Similarities | |
| Can only occur in eukaryotes | |
| DNA replication occurs first | |
| Production of daughter cells based on parent prison cell'southward genetic material | |
| 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 |
| i nuclear segmentation | 2 nuclear divisions |
| five phases | viii phases |
| Daughter cell identical to parent cell | Daughter cell not identical to parent jail cell |
| Results in 2 daughter cells | Results in iv daughter cells |
| Produces somatic cells | Produces germ cells |
| Occurs in asexual and sexual organisms | Occurs but in sexual organisms |
Wrapping Up Biology and Mitosis
We at present know that mitosis is the process of asexual cell replication that is responsible for an organism'due south development and growth, its cell replacement, and also, in sure organisms, asexual reproduction. Mitosis is, therefore, an integral office of eukaryotic performance. Mitosis differs from meiosis in that meiosis is the product of gametes, or sex cells, which volition allow for genetic recombination in sexual organisms. All the same, without mitosis, the embryos formed volition never grow to become organisms. Mitosis is preceded by Dna replication, to class two diploid sets of chromosomes. Mitosis has 5 phases. The first stage is prophase, where the chromatic cloth is released from the nucleus, and centromeres migrate to the poles of the cell. Prophase is followed by prometaphase, where the chromosomes migrate to align at the equatorial airplane of the cell. The third phase 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 2 identical daughter cells, genetically identical to the parent cell. Following this, the cell enters interphase, the stage between mitosis events.
Mitosis has given eukaryotic organisms the ability to regenerate cells as necessary without reducing the chromosome set while meiosis has immune the possibility of genetic recombination. Both are vital for the prevalence and continued survival of eukaryotic organisms.
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