What is the Difference Between Mitosis and Meiosis?
The cell is the basic units of life and for life to flourish, these cells reproduce copies of themselves through a cycle of growth and division. The entire cycle is known as the Cell Cycle. The cycle is divided into phases. The G1, S, G2, and M phases. The G1, S, and G2 phases are collectively called the Interphase. This phase is the phase where the cell grows, synthesizes, and replicates the genetic information in preparation for the cell to divide. The cell division proper starts at the M phase.
There are two types of cell division that happens in the M phase: Mitosis and Meiosis. These two divisions can occur in varying degrees depending on the organism. Some organisms rely solely on mitosis for survival, while some organisms rely on both. Prokaryotic organisms like bacteria, for example, rely solely on mitosis. Eukaryotic organisms like humans, dogs, birds, insects, and other higher organisms rely on both to survive.
Now, generally, mitosis and meiosis are similar in a sense. The result of both divisions are daughter cells and the same sequence of events occurs in both. Both divisions have stages that are closely similar. Mitosis starts with prophase, followed by metaphase, then anaphase, and ends with telophase and cytokinesis. Meiosis also goes through the same series of phases. Both divisions cover the breakdown of the nuclear membranes of the cells involved, the processing of the genetic materials for distribution to the daughter cells, the separation of two cells from one single cell, and the reformation of the once broken nuclear membrane.
However, as much as mitosis and meiosis are similar, they are also quite different. Mitosis is used when organisms grow and repair cells or when they produce asexually. The growth of hair, nails, torn tissues and muscles, clotting of wounds, and other functions related to growth and repair are all covered by mitotic division. Meiosis, on the other hand, is used solely for reproduction and creation of sex cells. The creation of sperm cells, egg cells, and the reproduction of organisms are covered by meiosis.
At the end of mitosis, two genetically identical daughter cells are formed. Cells that are the exact replica of the parents. However, at the end of meiosis, genetically different daughter cells are formed. Even when both divisions have the same stages, prophase, metaphase, anaphase, telophase, and cytokinesis. The meiotic division has a longer prophase in the first round of division compared to the second round. Meiosis also has a more complex process involved.
In mitosis, whatever genetic information in the parent cell there is, the daughter cells get a copy when they are produced. In meiosis, it is much more complicated than that. The first stage of meiosis, Meiosis I, generates variations on the genetic information that is passed on to the daughter cells. This is because during meiosis I, chromosome pairs are known as homologous chromosomes pair up. Of these two chromosomes, one chromosome comes from the father and the other from the mother.
There is also a process called crossing over that occurs in the meiosis I that does not happen in any of the stages of mitosis. In this process, the homologous chromosomes exchange genetic information. Because of this, the genetic information that gets passed to the daughter cells becomes a mix of two parents instead of a copy of either one.
The number of daughter cells that are produced between the two divisions is also different. Mitosis only produces two daughter cells while meiosis produces four out of the division. Each cell produced in mitosis is called a diploid cell since the exact number of chromosomes as the parents are retained in each of the two cells. Daughter cells of meiotic division, on the other hand, are haploid since they retain only half the number of chromosomes from the parents.
The area where they occur is also different. Mitosis happens in the body cells, meaning they can happen in all parts of the body, aside from the gonads. Meiosis occurs exclusively on the gonads and nowhere else.
Now, although the two divisions have similarities and differences, it does not revoke the fact that they are perhaps the essential processes that will ensure the continuation of life. If mitosis does not occur, then all damages rendered in an organism will not be repaired, eventually, the organism will die. Those who rely on mitosis for asexual reproduction will also cease to exist. Similar can be said of meiosis. When there is no meiosis, organisms will stop reproducing. When reproduction stops, it will lead to the decline of the species since as an older member of the species dies, there is no new generation to replace the dying or dead ones. Eventually, it will lead to extinction.
These scenarios are the main reasons why there are now innovations and steps done to ensure the smooth and orderly functioning of the entire cell cycle. There are now steps where mutations in either of the divisions are detected prior to ensure that the processes flow accordingly.