Meiosis is the process of cell division that creates offspring in sexually reproducing organisms, explains a University of Illinois at Chicago website. Unlike during mitosis, meiotic cell division starts with double the number of chromosomes in diploid parent cells. Meiosis cuts this number in half forming two haploid daughter cells. When these daughter cells combine and undergo fertilization, a zygote is created and the cell begins to develop.
Meiosis takes diploid parent cells, halves their genetic material, and combines the resulting daughter cells together. The end result is a zygote that consists of genetic material from both parent cells. After the zygote is formed, the organism returns to mitosis, or typical cell reproduction.
The process of meiosis has two main stages: Meiosis I and Meiosis II. Each stage is further broken down into four substages: Prophase, Metaphase, Anaphase and Telophase. Meiosis I involves the creation of the daughter cells from the diploid parent cells. In Prophase I, the chromosomes become visible, move toward the poles of the cell, the membrane disappears and chromosomes begin to swap genetic material. In Metaphase I, the genetic material attaches to centromeres in the cell. These centromeres begin to pull apart in Anaphase I, and they fully divide during Telophase I. Meiosis II involves the combination of the daughter cells. Each substage follows the pattern set in Meiosis I, but results in four haploid daughter cells with a standard amount of chromosomes.
Meiosis can be both sexual and asexual. One advantage of meiotic reproduction is that it can causes variation in the cell that could create new, beneficial adaptations. In this way, meiotic reproduction aids in natural selection.