Question

When is meiosis-I initiated?

Answer 1

Meiosis :

1. A special type of cell division that takes place in sexually reproducing organisms is called meiosis.
2. It produces gametes consisting of sperm or eggs with chromosome numbers 46 to 23. This is why human embryos have 46 chromosomes right from birth (fertilization between egg and sperm).
3. Meiosis provides the reduction of chromosome number in diploid cells.
4. From meiosis, we get haploid cells and these cells have half the number of chromosomes that are present in the parent cell.

Meiosis I:

1. Meiosis consists of two stages known as meiosis I and meiosis II.
2. Meiosis I is initiated after the replication of parental chromosomes to produce identical sister chromatids in the S phase.
3. It includes four steps.
4. Prophase I is further subdivided into leptotene, zygotene, pachytene, diplotene, and diakinesis
5. Metaphase I: chromosomes line up on the equator.
6. The orientation of the parent chromosomes and the chromosomes of each chromosome pair in this phase is random and can face any polarity.
7. Anaphase I: Homologous chromosomes segregate and each pole receives a random assortment of maternal and paternal chromosomes.
8. Each chromosome still contains a pair of sister chromatids, tied together by a common centromere.
9. Telophase 1: Nuclear membrane and nucleolus reappear, cell formation occurs and this is called a dyad cell.