Meiosis ll : Equational Cell Division

Meiosis II is the second phase of the cell division that separates the sister chromatids. Meiosis II is also known as equational cell division because the chromosome number at the end of meiosis II remains the same as at the end of meiosis I. It is a similar process of mitosis but genetic results are different for this process. In this process, a haploid parent cell divides into four genetically different haploid cells with non-duplicated chromosomes. Meiosis is responsible for forming the sperm and egg cells. This stage generally ensures genetic diversity. The process of meiosis consists of two stages: Meiosis I and Meiosis II. In this article, we will discuss Meiosis II and the different stages related to it.

Meiosis II

Meiosis II is the second stage of meiosis which is a specific cell division. It occurs specifically in the sexually reproducing organisms. The stage is responsible for the formation of gamete cells to sustain sexual reproduction. Meiosis II is also responsible for the genetic diversity in sexually reproducing organisms, particularly humans. In this process, a diploid parent cell divides into four genetically different haploid cells with non-duplicated chromosomes.

Meiosis II Diagram

At the time of Meiosis II, two haploid (n = 2) cells divide into four haploid (n = 2) cells. It is an important thing that these four haploid cells are genetically different from each other. In humans (2n = 46), we have 23 pairs of chromosomes. From the beginning till end, the number of chromosomes remains unchanged during the process of Meiosis II (n = 23).

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Stages of Meiosis II

Meiosis II is also known as equational cell division because it does not affect the chromosome number. The process leads to the formation of haploid cells. In this phase, two haploid cells go through further division which were created during the DNA replication process in the Meiosis stage I. Here are the four major stages of Meiosis II as mentioned below:

Prophase II

Prophase II starts after the process of cytokinesis of meiosis 1. In this stage, the daughter cells develop and get ready for the second round of division. At this phase, the spindle fibers develop after breaking the nucleus. The chromosomes become more condensed at this stage. At this phase, the nuclear membrane starts to disappear with the Golgi apparatus and ER complex.

Metaphase II

In Metaphase II, the chromosomes start to connect with the centriole through the microtubules. The chromosomes start to align along the middle of the metaphase plate.

Anaphase II

At the time of Anaphase II, the chromosomes start to split from the middle. The sister chromatids start moving to the opposite poles of the cell. The leading edge of the kinetochore pulls chromatids to the poles.

Telophase II

In Telophase II, the chromosomes start to dissolve again. At this phase, the chromosomes reach the opposite side completely. The cell divides into four unique haploid cells. It is the end of the entire meiosis process.

Significance of Meiosis II

The process of Meiosis II is responsible for the formation of gamete cells to sustain sexual reproduction. Here are the major significance of this particular stage as mentioned below:

• Meiosis II ensures the same number of chromosomes distribution in sexually reproducing organisms.
• The haploid gametes develop from a diploid cell.
• These gametes fuse afterward to create a new diploid cell.
• It also supports the restriction of chromosomal expansion.
• With Meiosis II, it is possible to preserve the stability of a particular species.

Difference Between Meiosis I and Meiosis II

Here we are going to discuss about the major differences between Meiosis I and Meiosis II:

Aspects	Meiosis I	Meiosis II
Purpose	Reductional division	Equational division
Preceding Events	Preceded by interphase	Preceded by Meiosis I
Number of Divisions	One	Two
Starting Cells	Diploid cells (2n)	Haploid cells (n)
Homologous Chromosomes	Homologous chromosomes pair and undergo crossing over	No crossing over, sister chromatids separate
Resulting Cells	Two haploid cells (n) with unique combinations of chromosomes	Four haploid cells (n), each genetically distinct
Chromosome Number	Halves the chromosome number	Maintains the chromosome number
Synapsis	Occurs during prophase I	Absent
Crossover	Occurs during prophase I	Absent
Separation of Chromatids	Homologous chromosomes separate	Sister chromatids separate
Genetic Variation	Increases due to crossing over and random assortment	Maintains genetic information from Meiosis I

What is Meiosis?

Meiosis is a specialized cell division process. It helps to produce gametes in sexually reproducing organisms. The meiosis process divides a particular cell by following two rounds that result in the creation of four genetically different haploid cells with non-duplicated chromosomes.

Why is meiosis called Reductional Division?

Meiosis is called the reductional division because the daughter cell’s chromosomes reduced to half of the parent cell. Meiosis is a special type of cell division. In this, each daughter cell receives half of the chromosomes from the parent cell after division. It means, the haploid daughter cells (n) are formed from a diploid parent cell (2n) during the process of cell division.

Conclusion

At the end of meiosis II, the chromosome number remain same. It is the second stage of meiosis. It occurs specifically in the sexually reproducing organisms. At the time of Meiosis II, two haploid (n = 2) cells divide into four haploid (n = 2) cells. It is an important thing that these four haploid cells are genetically different from each other. In humans (2n = 46), we have 23 pairs of chromosomes.

FAQs

What Happens in Meiosis II?

In meiosis II, a diploid parent cell divides into four genetically different haploid cells with non-duplicated chromosomes. Meiosis is responsible to form the sperm and egg cells. This stage generally ensures genetic diversity.

What is Meiosis II also Known as?

Meiosis II is also known as Equational Division. Meiosis II is the second stage of meosis which is a specific cell division. It occurs specifically in the sexually reproducing organisms.

What is the Difference Between Meiosis I and Meiosis II?

The starting cell of meiosis I is Diploid cells (2n) and starting cell of meiosis II is Haploid cells (n).At the time of Meiosis II, two haploid (n = 2) cells divide into four haploid (n = 2) cells.

What is the Second Meiotic Division?

The second meiotic division separates the two sister chromatids from each other. Meiosis II is the second stage of meiosis which is a specific cell division. It occurs specifically in the sexually reproducing organisms.

What are the Four Stages of Meiosis II?

There are four phases of meiosis II as prophase II, metaphase II, anaphase II, and telophase II. Meiosis II ensures the same number of chromosomes distribution in sexually reproducing organisms. Meiosis II is responsible for the formation of gamete cells to sustain sexual reproduction.

Why does Meiosis II Occur?

The meiosis II occurs to increase the number of daughter cells from two to four. Meiosis II is responsible for the formation of gamete cells to sustain sexual reproduction.

Where does Meiosis II Start?

Meiosis II begins with the two haploid cells. Meiosis II is also known as equational cell division since the process of cell division because the Chromosome number at the end of meiosis II remains the same as at the end of meiosis I.