Two Specific Ways That Mitosis Differs From Meiosis
- The first stage of both mitosis and meiosis is prophase. While the cell normally contains two strains of chromosomes prior to meiosis or mitosis (which is a period of time generally referred to as "interphase"), during prophase the chromosomes thicken and produce four pairs. The chromosomes become so thick during prophase that they become visible through a microscope. Before the chromosomes became thick, they had been in the nuclear membrane; during prophase, the nuclear membrane dissolves.
- During metaphase, the chromosomes line up beside each other in the middle of the cell. At this point in both meiosis and mitosis, the chromosomes are bound together in homologous pairs. A homologous pair contains two identical sets of chromosomes; this pair is what will split into new cells at the end of mitosis.
- In the anaphase, the bound chromosomes split apart and move to opposite sides of the cell. The spindle fibers in the chromosomes (which holds them by the poles of the cell) are what causes them to move.
- In telophase, the cell splits in half, with the same amount of chromosomes in each new copy of the cell. This happens during cytokinesis, in which the cytoplasm (liquid medium that holds all the cell's organelles) divides into two daughter cells (a "daughter" cell is another name for one of the two new cells formed during mitosis or meiosis).
- Meiosis differs from mitosis because the two daughter cells then split again, which results in the formation of four total cells. Thus, there is a second prophase, metaphase, anaphase and telophase in meiosis. In addition to sex cells in multi-cellular organisms, meiosis is one of the possible means of reproduction for eukaryotic (organisms with a cellular nucleus, as opposed to prokaryotes, which do not have a nucleus) single-celled organisms. The additional cells created during meiosis also leads to a larger possible gene variety in offspring.
- The result of the additional steps in meiosis ensures that the cells it creates are haploid. A haploid cell is a daughter cell that has only half the number of chromosomes as the original cell; in contrast, mitosis generally creates diploid cells, which means the daughter cells have the exact same number of chromosomes as the original cell. Meiosis has to create haploid cells in multicellular organisms because those cells combine with other haploid cells during sexual reproduction in order to create a new organism with a diploid cell.