Each species has a specific number of chromosomes.
In the human species, for example, 46 chromosomes are observed, of which 23 are acquired from the father and 23 are transmitted by the mother, the human being has 23 pairs of chromosomes.
Animals and humans are made up of two types of cells: somatic cells and reproductive cells.
Somatic cells are diploid cells that include all cell types in the body except reproductive cells, which are haploid cells and are different in men and women.
Haploid and diploid cells play an important role in the growth and reproduction of organisms.
The term meiosis means to decrease; This refers to the decrease in the number of chromosomes within the cell.
Meiosis is the process of chromosome reduction in eukaryotic cells (plants, animals, and fungi), leading to the production of germ cells (gametes / sex cells) necessary for sexual reproduction.
In meiosis, a double set of chromosomes (diploid) is reduced to a single set of chromosomes (haploid) to produce germ cells or spores.
When these combine in sexual reproduction, the resulting zygote is a diploid.
In this way, the chromosome number of the species is conserved through sexual reproduction.
Before meiosis begins, the chromosomes in the nucleus of the cell replicate.
This is because meiosis produces four daughter cells with half the chromosomes of the mother cell; or four single cell diploid haploid cells.
Meiosis begins in the same way as mitosis. After chromosome replication, all chromosomes separate into sister chromatids (the two identical halves of a chromosome).
However, here the similarities end. In meiosis, an additional process occurs: that of recombination or crossover.
In recombination, the chromosome pairs line up and recombine, so that each chromosome has a piece of another on it.
Therefore, meiosis uses recombination to produce four haploid daughter cells that are not identical to their diploid progenitor cells or to each other.
The so-called haploid cells are those that only have a complete chromosome set.
In these cells, we do not find the chromosomes in pairs, so homologous chromosomes are not produced.
In the case of humans, haploid cells are gametes that have only one chromosome set, that is, 23 chromosomes.
Haploid cells, also known as gametes or sex cells, are products of cell replication and division.
The resulting cells are reproductive cells: sperm and eggs will be used in sexual reproduction.
The importance of haploid cells is in the number of chromosomes of the gametes that unite at the time of fertilization.
The union of two haploid gametes in the fertilization of the human species allows the reestablishment of the number of chromosomes, which corresponds to a number of 46 chromosomes.
If the gametes were diploid, the number of chromosomes would double at each fertilization.
Haploid cells in animals are found in gametes, however, there are other organisms, where the haploid phase is present for much of their life cycle.
Chlamydomonas is an example of a protist that exhibits a haploid phase for most of its life cycle.
Diploid cells, on the other hand, are the most abundant cells found in animals and plants.
Diploid cells have two pairs of chromosomes and each pair is called homologous, since they have the same shape, size and the same genes.
This complete set of chromosomes (2n), is twice the number of cells in a haploid cell.
The daughter cells are exact replicas of the organism thanks to the process of mitosis.
Diploid cells, on the other hand, are all cell types in the human body with the exception of sex cells.
Examples of diploid cells include muscle, blood, and skin cells, called somatic cells.
Cell division and growth
During meiosis, a diploid germ cell divides to give rise to four haploid cells in two rounds of cell division.
This process of meiosis does not take place in organisms such as bacteria, the reproduction of these organisms is carried out by binary fission in asexual processes.
The development of haploid and diploid cells is an interconnected cycle that aids in growth and reproduction.
These cells result from the fusion of sperm and eggs, and carry the paternal and maternal chromosomes.
During the reproduction process, diploid cells undergo meiosis, which is a process in which one cell replicates and divides twice to form four haploid cells.
Once two haploid cells fuse during reproduction, the number of chromosomes in each cell fuse to produce a diploid cell, which undergoes mitosis for cell growth.