Oogenesis
The formation of the ovum (mature female gamete) from undifferentiated germ cells is called oogenesis. This process takes place in the ovaries (female gonads). Oogenesis consists of three stages known as the multiplication phase, growth phase, and maturation phase.
Cell Division
Cell division involves the formation of new daughter cells from the parent cells. It is a part of the cell cycle that takes place in both prokaryotic and eukaryotic organisms. Cell division is required for three main reasons:
Describe or diagram the sequence of events in meiosis (both divisions)
Step 1
Every cell has the power to grow and divide to form new cells of the same kind. At the time of this division, the genetic material is transmitted to the daughter cells from the mother cell. This is also necessary for body growth and the replacement of dead cells of the body. There are three types of cell division- (i) Amitosis, (ii) Mitosis, and (iii) Meiosis.
Step 2
In meiosis division, each mother sex cell with a diploid number of chromosomes divides by meiosis to form four daughter cells each with half the number of chromosomes. The entire process includes two divisions of the cell but the chromosome divides only once. These two division of the cell are- (i) meiosis I resulting in two daughter cells each with half the chromosome number, (ii) meiosis II during which each daughter cell divides into two, each chromosome of each daughter cell divides into chromatids which are equally distributed to two new daughter cells. Thus, four cells formed will have a haploid number of chromosomes.
The different stages of meiosis are as follows-
First meiotic division:
(a) Prophase I which is sub-divided into
- Leptotene
- Zygotene
- Pachytene
- Diplotene
- Diakinesis
(b) Metaphase I
(c)Anaphase I
(d) Telophase I
Interkinesis
Second meiotic division
- Prophase II
- Metaphase II
- Anaphase II
- Telophase II
Step by step
Solved in 4 steps
