Mitosis and Meiosis at first seem much alike for that they both are forms of cellular reproduction. Moreover, they go through similar stages such as interphase, prophrase, metaphase, anaphase, telophase, and cytokenisis. However, despite their similarities, these two processes are much different and have their own specific importance in cell reproduction. Mitosis evolved because it is a process that occurs in somatic cells and allows the division of a cell into two genetically identical daughter cells that are called diploids (2n) and have the total amount of chromosomes. In mitosis, the only difference between an animal cell and a plant cell will be during the cytokenisis stage. In an animal, cells are separated by a cleavage furrow, while they are separated by a cell plate in plant cells. Mitosis evolved within animals and plants to assure growth, cells repair, and the replacement of dead and damaged cells. Also, in plants, mitosis is important because haploids spores produced by meiosis grow into organisms that produce gametes by mitosis. Meiosis produces gametes in the sex cells of organisms, testes and ovaries in animals, and stamen and pistil in plants, and thus allows sexual reproduction. Cells produced by meiosis are called haploid for that they only have half the total amount of chromosomes (n).
The Essay on Cells. Mitosis. DNA
Instructions: Read chapter 3 in your textbook and review the lecture notes and study resources provided by your instructor. Type your answer in the answer block provided for each question. Answer blocks should expand as you type. If you experience difficulty typing in the provided answer blocks, you may type your answers in a new document. Save a copy of the completed activity to your computer for ...
They will later combine with another haploid to form a diploid zygote (n + n = 2n).
The big difference with mitotic cells is that cells produced by meiosis are not genetically identical. Cell differentiation is the process by which a daughter cell becomes different from its parent in appearance, function, or both. This is the reason why, for instance, a human offspring does not exactly look like his parents.
Meiosis is a really important process. The fact that it creates haploid cells permits to maintain the same exact number of chromosomes from generation to generation. If mitosis were the only cell reproduction process, diploid cells would fusion with another diploid during sexual reproduction resulting in an increase of the number of chromosomes in organisms throughout the generations. Also, meiosis is beneficial because it increases genetic variation through the production of new combinations of alleles, specifically crossing over during meiosis. Crossing over is the exchange of chromosome fragments at points called chiasmata between nonsister chromosomes of a pair of homologues. It results in the different combination of alleles in organisms. Independent assortment and random fertilization is also a way to obtain genetic variations. Finally, meiosis and crossover help prevent inherited disorders. Crossover can eliminate a disorder that a parent has and passes genetically. Thus, meiosis allows the positive evolution of species throughout the generations. On the other hand, the importance of mitosis is the maintenance of the chromosomal set. Each cell formed receives chromosomes that are alike in composition and equal in number to the chromosomes of the parent cell. Mitosis also helps the cell in maintaining proper size and equilibrium in the amount of DNA and RNA in the cell. Moreover, the growth of multicellular organism is due to mitosis. Mitotic cells are produced until the particular size has been reached. Again, the old, decaying and dead cells of the body are replaced by the process of mitosis.
Mitosis and meiosis have similarities but also some differences. In a general point of view, both mitosis and meiosis are mechanisms that describe cell division. Meiosis reduces the number of chromosome sets from one diploid to four haploids, whereas mitosis conserves the number of chromosome sets from one diploid to two diploids. Therefore, mitosis produces daughter cells genetically identical to their parent cell and to each other, whereas meiosis produces cells that differ genetically from their parent cell and from each other. In an organism that is n=8, a germ cell will have 8 chromosomes [n], half the total number found in a somatic cell (which would be in this case 16 [2n]).
The Essay on Differences Between Mitosis and Meiosis
Differences Between Meiosis and Mitosis Mitosis is a word from biology that means cell division. Another word, Meiosis, also comes from biology and means cell division. Cell is the basic unit and building block of all organisms. Cells have to divide because outside of the cell unable to keep up with the inside when the cell grows bigger. Cell division is conducive for the transportation of the ...
Then, a male and female gametes fusion together to form a diploid zygote with 16 chromosomes. The zygote will then develop and remain a diploid with 16 chromsomes (2n).
To reach those numbers, each process goes through stages (see image below).
Both, mitosis and meiosis, in their first stage of division, replicate DNA during interphase. However, in meiosis there is an additional second division during which the number of chromosomes remain the same, explaining why germ cells have only half the total number of chromosomes. Moreover, in meiosis,during prophase I, crossing over occurs between the non-sister chromatids (genes variation).
In mitosis, this synapsis of homologous chromosomes does not occur. Later on in the process, at metaphase I of meiosis, tetrads are positioned on the metaphase plate, rather than individual replicated chromosomes, as in mitosis. Finally, during meiosis, at anaphase I, sister chromatids, instead of separating like in mitosis, remain attached and the duplicated chromosomes of each homologous pair move toward opposite poles.
(This picture represents an organism that is 3=n, not 8=n. To be a good representation, on the meiosis diagram there should be 8 chromosome pairs through the whole stage of meiosis I and there should be 8 chromosomes in each cell (4) during the meiosis II stage. On the mitosis diagram, in order to properly represent an organism that is 8=n, there should be 16 chromosome pairs during prophase, and 16 chromosomes in each cell (2) at the end of the process.)
However, errors can occur in mitosis and meiosis. Non-disjunction can be found in both processes. It is the failure of chromosome pairs to separate properly during cell division. This could arise from a failure of homologous chromosomes to separate during meiosis I, or the failure of sister chromatids to separate during meiosis II or mitosis. Such an error would result in a cell with an unequal amount of chromosomes. Translocation is also another kind of error that can happen during meiosis. It occurs when a fragment of one chromosome is misplaced and attached to another chromosome. One disease related to this error is called Down syndrome. It results from trisomy 21, which means that each cell in the body has three copies of chromosome 21 instead of the usual two copies. The extra genetic material disrupts the normal course of development, causing the characteristic features of Down syndrome.
The Term Paper on Observing Mitosis And Meiosis On Cell Specimens
... will occur. The M phase of the cell cycle comprises of mitosis and cytokinesis. Meiosis contained a diploid cell that has two copies of each chromosomes and ... it produces four haploid cells containing ...
Mitosis and meiosis occur in two different and specific locations. Mitosis occurs in all the somatic cells of an organism. Indeed, in both animals and plants, this process is found in all the normal cells of a body that are not involved in sexual reproduction. Diploids are divided by mitosis to form more genetically identical diploids in order to repair cells and allow the general organism growth. Contrary to mitosis, meiosis occurs in sexually reproducing organs. In animals, meiosis occurs in the male and female sexual organs named testes and ovaries. In the testes and ovaries, meiosis produces germ cells that will combine with another haploid through sexual reproduction to form a diploid zygote. This zygote will replicate many copies of itself by mitosis in order to grow and develop, and become a complex animal. In plants, meiosis happens in the stamen (male) and pistil (female).
In the stamen, pollen grains develop by mitosis from spores that are formed by meiosis. In the pistil, the ovules are formed by meiosis. Then, the pollen grains (sperm) and an ovule (egg) fusion and create a diploid. This diploid will become a flowering plant by mitosis and will remain a diploid (2n).
MITOSIS
(On the mitosis diagram, in order to properly represent an organism that is 8=n, there should be 16 chromosome pairs during prophase, prometaphase, metaphase, and 16 chromosomes during anaphase and during telophase in each cell [2])
(This picture represents an organism that is 3=n, not 8=n. To be a good representation, on the meiosis diagram, there should be 8 chromosome pairs through the whole stage of meiosis I. During meiosis II, there should be 4 pairs of chromosomes in prophase II and metaphase II, and 8 chromosomes in each cell (2) of anaphase, and 8 chromosomes in each cell (4) of telophase.)
The Essay on Meiosis Daughter Cells
... chromosomes in a diploid cell resegregate, producing four haploid daughter cells. It is this step in Meiosis that generates genetic diversity. Meiosis 2 is similar to mitosis. ... Meiosis occurs during the formation of gametes in animals. Meiosis is a special type of cell division that occurs during formation of sperm and egg cells ...
