Reproductive function and biological meaning of meiosis

The reproductive function of the body is carried out in the process of combining two gametes (sex cells) when the daughter organism, a fertilized egg, originates and subsequently develops from the zygote. The sexual parental cells have a certain set of n-chromosomes. It is called haploid. Zygote, in accepting these sets, becomes a diploid cell, i. E. The number of chromosomes there is 2n: one maternal and one paternal. The biological significance of meiosis as a special division into cells is that it is thanks to it that a haploid cell is formed from diploid cells.

Definition

Meiosis in biology is usually called a kind of mitosis; Due to its diploid somatic cells of the genital glands are divided into 1n gametes. When the nucleus is fertilized, the gametes fuse. Thus, the 2n chromosome set is restored. The meaning of meiosis is to ensure the preservation of the chromosomal set and the corresponding amount of DNA inherent in each species of living organisms.

Description

Meiosis is a continuous process. It consists of two types of division, successively following one another: meiosis I and meiosis II. Each of the processes, in turn, consists of prophase, metaphase, anaphase, telophase. The first division of meiosis, or meiosis I, halves the number of chromosomes, i.e. There is a phenomenon of so-called reduction fission. When the second stage of meiosis occurs, or meiosis II, the haploidity of the cells does not threaten the change, it remains. This process is called the equational division.

All cells that are in the meiosis stage carry some information at the genetic level.

• The prophase of meiosis of the first is the stage of gradual spiralization of chromatin and the formation of chromosomes. At the end of this very complex action, the genetic material is present in its original form - 2n2 chromosomes.
• Metaphase comes - the maximum level of spiralization also comes. Genetic material remains unchanged.
• Anaphase meiosis is accompanied by a reduction. Each pair of parent chromosomes gives one of its daughter cells. The genetic material varies in composition, because The number of chromosomes became twice less: for every pole of the cell there are 1n2 chromosomes.
• The telophase is the phase, when the nucleus is formed, the cytoplasm is separated. The daughter cells are created, there are 2 of them, and in each 2 chromatids. Those. The set of chromosomes in them is haploid.
• Then there is interkinesis, a small respite between the first and second stages of meiosis. Both daughter cells are ready to enter the second stage of meiosis, which proceeds according to the same mechanism as mitosis.

The biological significance of meiosis, therefore, lies in the fact that in its second stage, as a result of complex mechanisms, there are already 4 haploid cells - 1n1 chromosomes. Ie, one diploid maternal cell gives life to four - each has a haploid chromosome set. In one of the phases of meiosis of the first degree, the genetic material is recombined, and in the second stage chromosomes and chromatids move to different poles of the cell. These movements are a source of variability and various intraspecific combinations.

Results

So, the biological significance of meiosis is indeed great. First of all, it should be noted as the main, main stage of gamete genesis. Meiosis provides the transfer of genetic information of species from one organism to another, provided that they reproduce sexually . Meiosis gives rise to intraspecific combinations, because Daughter cells differ not only from their parents, but also differ from each other.

In addition, the biological significance of meiosis lies in the reduction of the number of chromosomes at the time when the sex cells are formed. Meiosis ensures their haploidity; At the time of fertilization in the zygote, the diploid chromosome composition is restored.