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Meiosis

Meiosis is a cell division in which the number of chromosomes is half. meiosis i If parent cell is diploid, daughter cell haploid will be formed after division.
Importance of Meiosis- The importance of meiosis lies in the formation of male gametes and female gametes, both of which form a zygote by which a new child is born. This is a kind of sexual reproduction.

There are two types of meiosis
1- meiosis 1
2- meiosis 2
Mitosis causes one type of division, but two types of division in meiosis.
meiosis 1 has different stages
1- Prophase 1
2- metaphase 1
3- anaphase 1
4- telophase Phase 1
prophase 1 is again divided into 5 steps
1- leptotene – is inside the cell and there is a chromosome inside the center. Suppose the cell we are taking information about has four chromosomes and each chromium is connected to its sister chromatic and this chromosome is interconnected. Will come close to each other called homologous pair
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2-zygotene – In this phase when homologous pair come close to each other, they form synapsis.
3-pachytene- In this stage the segments of chromosomes are changed which form the structure of V shape called chaismata.
4-diplotene – In this stage the chromosome starts to separate from each other
5-diakinesis – in this stage the chromosomes completely separate from each other
metaphase 1- In this stage the nuclear membrane will disappear as well as mitotic apparatus like centrioles will be 2 fold and Aster and spindle fibre will also be formed! In this phase all chromosomes will be interrupted. Equitorial plates will also be formed in this phase.
Anaphase 1- In this step the spindle fibers pull the chromosomes apart so that a chromosome will move along its centromere towards the pole.
Telophase 1- In this stage the cell will divide into both nuclei.
cytokinesis- When the nucleus is divided followed by the division of cytoplasm which we call cytokinetics, by this division two progeny cells are formed.
After meiosis1, meiosis 2 begins, which we also call mitotic division. In this phase, the functions are similar to mitosis and form four progenitor cells.
meiosis 2 also has four stages
1- prophase 2
2- metaphase 2
3- anaphase 2
4- telophase 2
In this way we can say that there is twice division in meiosis which is made up of 4 progenitor cells.


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