In any breeding species, the number of chromosomes is always constant — why so? What role do chromosomes play? What is mitosis and meiosis? Let's find out. We present to your attention a small biology lesson in the article below.
Mitosis and meiosis
The difference between both types of cell division is how the chromosomes are separated, that is, hereditary material at the time of division.
Thus, during cell division by mitosis, the two daughter cells obtained always contain the same number of chromosomes as the parent cell from which they are derived. This is why cells have a constant number of chromosomes.
Mitosis is a type of division of all cells in our body, with the exception of cells located in the ovary and testicles.
Its role is to maintain a constant number of chromosomes in each cell, even after division. Cells have a constant number of chromosomes - why is this important? There is one main reason. Mitosis allows us to grow and independently support our bodies. This is why cells have a constant number of chromosomes.
Meiosis
During cell division by meiosis, the number of chromosomes does not remain constant, but rather decreases by half. This is a reduction type of cell division, and therefore, at the end of the whole process, each daughter cell obtained contains only half the number of chromosomes from the original cell. That is, from cells that contained 46 chromosomes grouped into 23 sets, cells were obtained that contain 23 chromosomes.
Meiosis is a type of cell division during which only cells located in the ovaries and testicles are used.
Their role is to reduce the number of chromosomes to half, so during fertilization: 23 chromosomes from the mother + 23 chromosomes from the father combine to form 46 chromosomes necessary for human formation. This explains why cells have a constant number of chromosomes even after division.
Through meiosis, we get gametes, which our body cells use for fertilization and reproduction. In females, these cells are called oocytes (ovules), while in males they are called spermatozoa.
Chromosomes: why is their number in the cell constant?
It is worth noting that this is a special type of cell division, and in the whole body it is used only by germ cells, that is, cells located in the woman’s ovary and in the man’s testicles.
In other words, the cells that are located in the organs participate in reproduction, and their function is to constantly maintain our number of chromosomes from generation to generation. Otherwise, the number of chromosomes will have a twofold increase in each generation, it will be incompatible with life.
A bit about chromosomes
An organism with any multiple diploid number of chromosomes is considered polyploid. Polyploidy is a normal evolutionary strategy for many plant groups, but it is quite rare in animals. Examples of polyploid plants and animals are potatoes (Solanum tuberosum), an African clawed frog (Xenopus laevis), and a rat whisker (Tympanoctomys barrerae). However, in most animals, any deviation from the typical number of chromosomes for a species may be accompanied by changes - sometimes quite dramatic for the body. For example, people often have a miscarriage, whose number of chromosomes is not normal,
The number of chromosomes does not correlate with the apparent complexity of the animal or plant: in humans, for example, the diploid number is 2n = 46 (i.e. 23 pairs) compared to 2n = 78 or 39 pairs in a dog or 2n = 36 (18) in a common earthworm .