Meiosis is a specialized type of cell division that occurs in sexually reproducing organisms.
How does meiosis happen ?
During meiosis I, homologous chromosomes pair up and undergo crossing over, leading to the exchange of genetic material between them. This exchange of genetic material contributes to genetic variation in the offspring.
Prophase I:
- Leptotene: The chromatin condenses into long, thin threads called chromosomes.
- Zygotene: Homologous chromosomes pair up, forming bivalents.
- Pachytene: Synaptonemal complexes form between homologous chromosomes, aligning them precisely.
- Diplotene: The synaptonemal complexes break down, allowing some homologous chromosomes to exchange segments of genetic material through a process called crossing over.
- Diakinesis: The chromosomes become fully condensed and visible.
Metaphase I:
The bivalents align at the equator of the cell, forming the metaphase plate.
Anaphase I:
Spindle fibers attach to the kinetochores of each chromosome, pulling the homologous chromosomes to opposite poles of the cell.
Telophase I:
The nuclear envelope reforms around each set of chromosomes, resulting in two haploid cells with a single set of unpaired chromosomes each.
Meiosis I results in two haploid daughter cells, each with a unique combination of genetic material due to crossing over and independent assortment.