- It maintains the same chromosome number in the sexually reproducing organisms.
- It provides a way for mixing up of genes, which occurs in two ways: the maternal and paternal chromosomes gets mixed up and cross joining.
1. It maintains the same chromosome number in the sexually reproducing organisms. From a diploid cell, haploid gametes are produced which in turn fuse to form a diploid cell.
2. It restricts the multiplication of chromosome numbers and maintains the stability of the species.
3. Maternal and paternal genes get exchanged during crossing over. It results in variations among the offspring.
4. All the four chromatids of a homologous pair of chromosomes segregate and go over separately to four different daughter cells. This leads to variation in the daughter cells genetically.
Phases of Meiosis II
The second meiotic division is very much similar to mitosis. It has the following steps:1. Prophase II
The events of prophase II are similar to mitotic prophase.
Nucleolus and nuclear membrane disappear.
Spindle fibres are formed at each pole.
2. Metaphase II
Chromosomes move to the centre of the equatorial plane.
They get attached to spindle fibres centromere.
3. Anaphase II
The sister chromatids separate from one another and are pulled to opposite poles of the spindle due to the contraction of the spindle fibres.
4. Telophase II
The chromosomes begin to uncoil and become thin.
They reorganize into the nucleus with the reappearance of the nucleolus and nuclear membrane in each pole.
Cytokinesis follows and four haploid daughter cells are formed and thus the meiotic division is completed.