Concept, Phases and What is mitosis

We explain to you what is meiosis and what each of its phases consists of.Also, what is mitosis and its differences with meiosis.

Meiosis provides genetic variety in the descending cells.

What is meiosis?

Meiosis or meyosis is called one of the ways in which cells reproduce , characterized by providing genetic variety in the descending cells, which is key to sexual reproduction: the one that involves two different individuals to produce a new one, whose genetic material will be a combination of the previous two.

The meiosis consists in the division of a diploid cell (2n) , that is, provided with two sets of chromosomes (most of our cells are of this type), in four haploid cells (n), that is, provided with half of the genetic load of the previous cell.

These haploid cells operate as a seed of a new individual, once it is merged with another from another individual, each contributing half of its genetic load.This is how gametes, animal reproductive cells and of the human being.

Thus, meiosis is a process prior to sexual reproduction , since gametes are formed in it (ovules and sperm, for example).However, it is also part of cycles of complex life, in algae, fungi and other simple eukaryotes, to achieve some generational alternation, reproducing their cells in a sexual and asexual way in different stages.

The meiosis was discovered in the 19th century by the German biologist Oscar Hertwig (1849-1922), from his studies with sea urchin eggs.Since then successive research contributed to understand it better and to understand its vital importance in the evolution of higher forms of life.

See also: Eucariot Cell.

Phases of meiosis

Meiosis I results in cells with half the genetic load.

Meiosis is a complex process that involves two distinct phases: meiosis I and meiosis II.Each of them is composed of several stages: prophase , metaphase, anaphase and telophase.This merits a more detailed study:

• Meiosis I.First cell division of the diploid (2n), known as reductive, as it results in cells with half the genetic load (n).


• Prophase I.The first step consists in preparing the DNA to become two different sets, so that the genetic material intersects and a sort of dividing line emerges in the cell.


• Metaphase I.The chromosomes are located in the center of the cell (equator) and begin to separate.The random genetic distribution has already been carried out.


• Anaphase I.Each string of DNA tends to a cell pole, forming two haploid poles (n).


• Telophase I.The plasma membrane separates and gives rise to two haploid cells.


• Meiosis II.Known as a duplicative phase, as it resembles mitosis: two whole individuals are formed by duplicating the DNA.


• Profase II.Haploid cells created in meiosis I condense their chromosomes and break the nuclear envelope.


• Metaphase II.As before, chromosomes tend towards the middle of the cell, preparing for a new division.


• Anaphase II.The genetic material tends to separate and migrate to the cell's poles, enlisting the new process of cell division.


• Telophase II.The cell membranes separate again and result in four haploid cells (n), each with a different distribution of the individual's complete genetic code.

Meiosis and mitosis

Mitosis produces cellular "clones" and is considered asexual reproduction.

The differences between mitosis and meiosis are several:

• Mitosis is asexual.Mitosis consists in the division of an original cell to form two genetically identical, from a total division of the individual.This form of reproduction produces cellular "clones" and is considered asexual, because it does not add variety to the genetic well.Meiosis, on the other hand, is the preparation for sexual reproduction and therefore allows high genetic recombination.


• Mitosis creates two individuals, both diploid.meiosis instead produces four, but all haploid.


• Mitosis preserves DNA.As stated before, mitosis is a mechanism for preserving intact genetic material, while meiosis subjects it to a recombination process in which error is much more possible, but that It also enriches the genome and allows the creation of particularly successful chains.

See more: Mitosis.