Before discussing about Meiosis, it is worth understanding the basics of cell division. By now we know cells, also known as the ‘basic unit of life’ is present in all living organisms and genes refer to the ‘basic unit of heredity’. During the process of cell division, genetic material like the DNA is distributed in the two daughter cells. Bear in mind that all living organisms arise from pre-existing cells. Mitosis is the process that defines the generation of new cells while meiosis strictly sticks to the concept of reproduction. The process of generating gametes for the purpose of reproduction is called Meiosis.
Meiosis can also be defined as a unique and special type of cell division. During the event of meiosis, the chromosome count shrinks to half. All eukaryotes including both single-celled and multi-cellular living organisms like plants, animals and fungi, capable of reproducing witness meiosis. This type of cell division facilitates the production of germ cells like sperms and eggs. However, there is an abrupt cut-down in the amount of genetic material as well. Right before the occurrence of meiosis, there is a stage known as the S phase, also popular as the DNA Replication Phase of a cell cycle. Just as the name suggests, the chromosome in this stage are replicated, each comprising of two identical sister chromatids, tied to the centromere.
To simply the subject further, Meiosis is divided into two stages – Meiosis 1 and Meiosis 2. These stages are again subdivided into four phases – Prophase, Metaphase, Anaphase and Telophase. In the first stage of Meiosis 1, there occurs a pairing up of homologous chromosomes, also allowing the exchange of genetic material, often termed as ‘Crossing Over’. This is definitely not the end of stage 1. The paired chromosomes are then stretched apart into the two daughter cells which contain half the chromosome count of a parent cell.
Ultimately, during the stage of Meiosis, the sister chromatids tend to stay attached unless there is a repeated event of crossing over. Unlike the first stage of meiosis, there occurs further division of cells produced during Meiosis 1. The sister chromatids then detach and generates a total of four daughter cells. With time, these cells develop into mature reproductive cells like pollen, spores or gametes. The entire even of division and generation of reproductive cells describe Meiosis 2.
The study of meiosis support great innovations in the field of human medicine.