Mitosis is a process by which a cell replicates itself to make two identical daughter cells. Each daughter cell has its entire genetic information. Meiosis, on the other hand, creates four gametes, or sex cells, with half the original cell’s chromosomes. These gametes then fuse to form a fertile egg.
During meiosis, the two daughter cells produce by meiosis I undergo events of meiosis II in synchrony. In the S phase of meiosis, DNA replication takes place. This replication creates identical sister chromatids that remain together through a process known as sister chromatid cohesion.
Although meiosis is the more common type of cell division, it is not a necessity for asexual reproduction. In animals, meiosis is the process that produces egg cells and zygotes, the next generation of a species. Both processes are used by animals and plants. While animals need to perform meiosis for reproduction, plants need both processes to produce gametes.
Once the cells have finished mitosis, they enter the anaphase. These cells have the same genetic information as their original cell, but are diploid. These cells can then go through the interphase again, replicate their DNA and create centrosomes. This is the process by which most cells grow in the body. However, some species employ both processes. It is important to understand both processes.
The process of meiosis results in variation on the chromosomes, which are homologous. The first set of chromosomes is carried by the mother’s egg, while the other one carries the DNA of the father. This resulting multicellular offspring has a mixture of paternal and maternal genes. Multiple crossovers in an arm of the chromosome have the same effect.
In the second step of the mitotic cycle, a cell divides into two new nuclei. The sister chromatids line up along a linear plane through the middle of the cell. At this stage, a spindle, which acts as the center of the cell, forms between the centrosomes at the ends. Microtubules are poised to pull the sister chromatids apart.
The origin of meiosis is unknown, but a meiotic process could provide information on the evolution of sexual reproduction in eukaryotes. Biologists disagree about the origin of sex in eukaryotes. The basic function of sex is unknown, as is the reason for retaining sex. But meiosis was developed more than 1.2 billion years ago, and descendants of those early sexually reproducing species still exist.
DNA replication takes place during the S phase. Sister chromatids are tightly attached to each other at the centromere region. Centrosomes are also duplicated during the S phase. Centrosomes are rod-like structures made up of tubulin that sit at right angles to the cell’s cytoplasm and give rise to the mitotic spindle.
Meiosis and mitosis are two different processes, but both processes produce gametes with 32 chromosomes. Both processes require a cell cycle that allows them to divide. Cells enter and exit different phases depending on external factors. Cells must clear different checkpoints to proceed. If one of these checkpoints is missing, meiosis will not occur.