Definition
Meiosis is the process in which one cell undergoes division two times for the production of four cells containing half the original quantity of the genetic information. These newly formed cells are sex cells, that is, eggs in females and sperm in males.
It is the method of gamete formation in which a 4n cell is divided into four different haploid daughter gametes that are non-identical. The daughter gametes are haploid (n) in nature.
(Image Will be Uploaded soon)
Do you Know?
Meiosis is extremely important as that creates the correct number of chromosomes in the course of sexual reproduction. Genetic variation is ensured in the recombination process. Such variation is further enhanced with the unification of gametes in fertilisation. The constant combination of parental DNA in case of sexual reproduction has led to today’s incredible diversity in organisms on Earth.
To understand what meiosis is, let us take a look at its different stages.
There are 6 stages of meiosis into every cell division – Prophase, Prometaphase, Metaphase, Anaphase, Telophase and Cytokinesis.
Meiosis I
Meiosis I is the initial round of nuclear division, which is also called reduction division. It is because resulting cells retain only half of the chromosomes as compared to the parent cell.
Prophase 1
It involves the disintegration of the nuclear envelope and the condensation of chromosomes. On chromosome division, spindle fibre appears.
Prometaphase I
Chromosomes and spindle fibres are attached, and the points of attachment are called centromeres. Here, the condensation of chromosomes continues.
(Image Will be Uploaded soon)
Metaphase I
The paternal and maternal chromosomes, which are held as homologous chromosomes, randomly align along the equator of the cell. This random assortment is the cause of genetic diversity within offspring.
(Image Will be Uploaded soon)
Anaphase I
The homologous chromosomes migrate towards the opposite poles of the cell, and spindle fibre retracts for subsequent DNA division.
(Image Will be Uploaded soon)
Telophase I and Cytokinesis I
The nuclear envelope modifies leading to the disappearance of spindle fibres in telophase I. Two non-identical diploids (2n) daughter cells emerge from cell division in cytokinesis I.
(Image Will be Uploaded soon)
Meiosis II
The two cells further undergo division and are termed as equational division. In equational division, chromosome numbers in the daughter cells are not reduced. Moreover, it gains the same number of chromosomes as there are in the "parent cell" which entered into meiosis II.
Prophase II and Prometaphase II
Identical to the same stages in meiosis I and what is meiosis definition
Metaphase II
Along the cell equator, chromosomes are lined up in a single file.
(Image Will be Uploaded soon)
Anaphase II
After splitting of chromosomes, the produced sister chromatids are stretched to opposite poles of the equator.
(Image Will be Uploaded soon)
Telophase II
Identical the same stage in meiosis I
Cytokinesis II
Two non-identical haploid daughter cells are produced on cytoplasm and cell division. As it concurrently takes place in two cells, identical haploid daughter cells emerge.
(Image Will be Uploaded soon)
Test Your Knowledge
i. Which of the following relates to chromosome movement in Metaphase?
(a) Congression.
(b) Repulsion.
(c) Equalisation.
(d) Polarisation.
ii. Which of the following takes place in Anaphase 1 stage?
(a) Centromere is first to separate.
(b) Chromatids separate towards one pole.
(c) Each homologue moves towards the opposite pole.
(d) Chromosomes separate into four cells.
Solutions
i. (a) Congression.
ii. (c) Each homologue moves towards the opposite pole.
Learn more about meiosis and other related topics through our online classes. You can also download free pdf solutions that will enhance your knowledge. All you have to do is install the Vedantu app now!
Relevance of Meiosis
Meiosis is responsible for the formation of gametes. During meiosis, chromosomes from the parent cells are distributed equally in the cells. Meiosis is responsible for lending diversity in the different species as the unique arrangements of chromosomes result in unique offspring. This causes variation in all species. All students who need to take up biology later on in life to further their career need to know about meiosis.
FAQs on Stages of Meiosis
1. How can students revise the chapter on Meiosis before an exam?
All students can read from Stages of Meiosis - Definition, 6 Stages and FAQ on Vedantu. This page has explained what meiosis is and its stages well and can be used by the students to understand all the important concepts in a proper manner. All the useful information here is free of cost for the students and has been explained in simple terms. Only expert Biology teachers have contributed towards the study of Vedantu and so, it contains reliable inputs about the topics and sub-topics that it has.
2. What is metaphase in Meiosis?
Among the many different phases and stages of meiosis, metaphase is also a phase. It is a stage during the process of cell division. During the metaphase, the chromosomes condense and become distinguishable as they align in the center of the dividing cell.
3. What are gametes?
Gametes are used for the purpose of reproduction and are also known as sex cells. Thus, an organism’s reproductive cells are termed gametes. Female gametes are called ova or egg cells and male gametes are called sperm.
4. How many stages of meiosis are there?
There are about six phases of meiosis. They are prophase, prometaphase, metaphase, anaphase, telophase and cytokinesis. During prophase, differences from mitosis begin to appear and by the final phase i.e. cytokinesis, chromosome sets are split into two cells.
5. Where can students find some questions on meiosis?
Students can go to Stages of Meiosis on Vedantu and then look for some questions on the same. This page is the answer to all their queries regarding Meiosis as it has included all the useful bits of information that the students need to be aware of. All questions on Meiosis have been explained well here so that the students understand how they will come during tests. This page is a great mode of revision for all students of Biology. This page is a great mode of revision for all students of Biology as it prepares them in the right manner before an exam on the topic. Solving questions become important before a test so that the students know what they have learned.
6. What is the Number of Times of Cell Division in Meiosis?
In meiosis, one cell divides twice leading to four cells. These four cells include half of the original genetic information. Daughter cells are formed when a single cell divides twice during meiosis.
7. Which Cells are Generated After Meiosis?
After meiosis, haploid daughter cells are produced with differing sets of chromosomal combinations from the parent chromosomes. Four haploid gametes are created in sperm cells.
