What Are the Differences Between Mitosis and Meiosis?

Meiosis is a division in which the number of chromosomes in a cell is halved. When a germ cell divides, the chromosome replicates only once, and the cell divides twice in succession. This is a special way of dividing the number of chromosomes in half. Meiosis is not only a mechanism to ensure the stability of the chromosome number of a species, but also a mechanism for the species to evolve continuously in response to environmental changes. As a result of meiosis, the number of chromosomes in mature germ cells is reduced by half compared to primitive germ cells. Meiosis ranges from organisms that have sexual reproduction; the period is the development from primitive germ cells to mature germ cells.

Meiosis (meioSIs) is closely related to the sexual reproduction of plants and occurs only in germ cells. As a result of division, the number of chromosomes in each daughter cell is only half that of the mother cell, so it is called meiosis. The entire process of meiosis undergoes two cell divisions. The first time is that each pair of homologous chromosomes in the mother cell is paired and arranged to the equatorial plane. At the same time, each chromosome is tandemized into two, becoming two daughter chromosomes, but The two monomers are still juxtaposed without being separated. Then, the paired paired chromosomes are moved to one end, and finally two daughter cells are generated, and the number of chromosomes in each daughter cell is half that of the mother cell. In the second division, the two subchromosomes juxtaposed in each chromosome of the daughter cells began to separate, moved to one end, and carried out a process similar to mitosis. Finally, each daughter cell divided into two cells, resulting in four cells. The number of chromosomes in each cell becomes haploid (n) ^[1]

Non-identical chromosomes during meiosis

Overview

Meiosis is a process in which DNA is copied once, and cells divide twice in succession to form

Note: Meiosis can be divided into two stages,

Overview of Changes in Meiosis
Compare items	Spermatogonia	Primary spermatocyte					Secondary spermatocyte				Sperm cell
Compare items	Spermatogonia	Interphase	Prophase	Mid-term	Late	Final period	Prophase	Mid-term	Late	Final period	Sperm cell
Chromosome changes	2N	2N	2N	2N	2N	N	N	N	2N	2N-N	N
DNA molecular changes	2A	2A-4A	4A	4A	4A	2A	2A	2A	2A	2A-A	A
Chromatid changes	0	0-4n	4n	4n	4n	2n	2n	2n	0	0	0

Pre-meiotic interval

It can be divided into three phases: G1, S, and G2. According to modern cell biology research, the interphase of cell division is divided into three phases: the first interstitial phase, called G1 phase; the synthetic phase, called S phase; The G1 and G2 phases mainly synthesize related proteins and RNA, and the S phase completes DNA replication.

First, the stability of the number of chromosomes between individual generations of sexually reproducing organisms is guaranteed. By meiosis, the number of chromosomes in sex cells (gametes) is halved, that is, 2n (n is one

Meiosis is the basis of genetics. Specifically in:

1. In the process of meiosis, because the homologous chromosomes are separated, they enter different

1 Cells divide twice in succession during meiosis, while cells divide only once during mitosis;

2. The result of meiosis is halving the number of chromosomes, while the result of mitosis is the same number of chromosomes;

3 After meiosis, a cell becomes four daughter cells containing different combinations of genetic material (considering non-sister chromatid fragment exchange in the tetrad) or two identical daughter cells (excluding monomer fragment exchange). After mitosis, a cell only forms two daughter cells with the same genetic material;

4 During meiosis, there are unique homologous chromosome pairings and local exchange between homologous non-sister chromatids, while mitosis does not

5. Meiosis occurs in the animal testis or ovarian primordial germ cells (higher males occur in the testes, higher plants occur in anthers and ovules), and mitosis occurs in somatic cells (when the primordial germ cells, that is, the protoblasts, proliferate Belongs to mitosis).

6. When the primary oocyte divides, the cytoplasm divides unevenly and a second polar body is produced. The second polar body will gradually disappear, while mitosis does not produce this phenomenon.

How to distinguish between mitosis and meiosis

1. Look at the number of chromosomes: if it is odd, it must be the second division of meiosis (but the number of chromosomes in stage II is not necessarily an odd number), otherwise it may be mitosis or the first division of meiosis;

2. Look for homologous chromosomes: if not, it must be the meiotic second division. (Looking left and right)

1. Have

Preparation of gonogen cells,

Primary mother cells first associate.

After sorting the same source,

Since then the dyeing is unpaired.

The second mother seems to be the same as Yousi,

The plate then cracked.

The sisters said goodbye to each other,

Once again, I'll take the West and East.

Stained with multiple cells,

The number is halved by homology.