Notes On Meiosis - II - CBSE Class 11 Biology
Meiosis is also known as reduction division as the number of chromosomes is reduced to half in the daughter cells. Meiosis two is divided into four phases – prophase two, metaphase two, anaphase two and telophase two. Meiosis one results in two haploid daughter cells, followed by meiosis two, which results in four haploid cells.
 
Meiosis two resembles mitosis as the same number of chromosomes is retained in the daughter cells. Between the two meiotic stages, there is a short-lived resting stage known as interkinesis, followed by prophase two, where the chromosomes get thicker, shorter and distinct, with each chromosome consisting of two chromatids. By the end of this phase, the nucleolus disappears and the nuclear envelope disintegrates.

During metaphase, the chromosomes align themselves along the equatorial plane, and spindle attach themselves to the kinetochores of the sister chromatids. During anaphase, the centromere of each chromosome divides longitudinally into two and splits the chromosome into two daughter chromosomes, which are then pulled to the opposite poles.

During telophase, the chromosomes reach the opposite poles and a new nucleus with a nuclear membrane is organised at each pole. All four nuclei differ from each other in genetic aspects due to the crossing over in prophase one. Telophase two is generally followed by cytokinesis, during which the cytoplasm in each cell is equally divided, resulting in the formation of four haploid daughter cells.


Meiosis in germ cells followed by the fertilisation of gametes restores the chromosome number in the offspring of sexually reproducing organisms. 

Summary

Meiosis is also known as reduction division as the number of chromosomes is reduced to half in the daughter cells. Meiosis two is divided into four phases – prophase two, metaphase two, anaphase two and telophase two. Meiosis one results in two haploid daughter cells, followed by meiosis two, which results in four haploid cells.
 
Meiosis two resembles mitosis as the same number of chromosomes is retained in the daughter cells. Between the two meiotic stages, there is a short-lived resting stage known as interkinesis, followed by prophase two, where the chromosomes get thicker, shorter and distinct, with each chromosome consisting of two chromatids. By the end of this phase, the nucleolus disappears and the nuclear envelope disintegrates.

During metaphase, the chromosomes align themselves along the equatorial plane, and spindle attach themselves to the kinetochores of the sister chromatids. During anaphase, the centromere of each chromosome divides longitudinally into two and splits the chromosome into two daughter chromosomes, which are then pulled to the opposite poles.

During telophase, the chromosomes reach the opposite poles and a new nucleus with a nuclear membrane is organised at each pole. All four nuclei differ from each other in genetic aspects due to the crossing over in prophase one. Telophase two is generally followed by cytokinesis, during which the cytoplasm in each cell is equally divided, resulting in the formation of four haploid daughter cells.


Meiosis in germ cells followed by the fertilisation of gametes restores the chromosome number in the offspring of sexually reproducing organisms. 

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