What is Mitosis?Mitosis is the cycle that eukaryotic cells go through in order to divide. During mitosis, a cell duplicates its DNA and divides into two genetically identical cells. Mitosis is typically followed by cytokinesis, which divides the other properties of the cell including cytoplasm, organelles and the cell membrane. Karyokinesis also occurs, which divides the nucleus. Mitosis and cytokinesis are part of the mitotic phase of the cell cycle, which make up about 20 percent of the entire lifecycle of a cell. The end result of mitosis is two completely separate cells with equal and similar cellular components.
What is Meiosis?Meiosis is the special cell division cycle for gamete cells, or sex cells. Chromosomes carry the genetic code for an organism, and come in pairs. In asexual reproduction, a cell will just divide itself to create two new cells. However, for sexual reproduction, gamete cells are necessary. In sexual reproduction, the parent provides one set of each chromosome, or half the genetic code for an organism. When the two parent donor gametes – typically an egg and sperm – meet in fertilization, they provide the offspring with the full set of necessary chromosomes. For example, humans require 46 chromosomes, or 23 pairs. An egg or sperm will have just 23 chromosomes, or one half of the pair. This makes gamete cell division more complex than ordinary cell division. Within this cycle, the number of chromosomes is halved, typically going from a diploid (two sets) to haploid (one set) cell. It also includes a step where the chromosomes cross, allowing for more genetic diversity in reproduction. The Stages of MeiosisMeiosis has two stages: meiosis I and meiosis II. The cells are divided during both stages. These stages are similar to the mitosis stages. Just like mitosis, prior to meiosis, each chromosome’s DNA is replicated during the S phase. During meiosis, the parent cell begins with the full set of chromosome pairs, so in humans it will be 46. During the S phase, the number of chromosomes double, so each cell will have two copies of each chromosome, similar to mitosis. However, soon the differences between the two begin to emerge. The basic process of meiosis begins when the homologous, or the copies of each chromosome, exchange genetic material, which is known as crossing over, in order to provide genetic diversity. After this, the pairs separate as two cells are formed, each with one set of chromosomes. Then, the chromosomes split into two again to form to haploid cells that include just one set of chromosomes. At the end of meiosis, four genetically distinct haploid cells are produced, which then will mature into gametes.The phases of meiosis have similar names to that of mitosis. Meiosis I, in a process very similar to mitosis, begins with prophase I, which is when the chromosome crossover occurs. The cell then moves into metaphase I, which is when the chromosomes line up in the equatorial plane in preparation for separation. The next stage is anaphase I, which is when the chromosomes are separated and the cell begins to elongate to divide. Telophase I is when the division completes, which each cell having a complete set of chromosome pairs. Now, it is time for meiosis II. The m