[mahy-toh-sis] 
| the usual method of cell division, characterized typically by the resolving of the chromatin of the nucleus into a threadlike form, which condenses into chromosomes, each of which separates longitudinally into two parts, one part of each chromosome being retained in each of two new cells resulting from the original cell. |
mitosis mi·to·sis (mī-tō'sĭs)
n. pl. mi·to·ses (-sēz)
The process in cell division by which the nucleus divides, typically in four stages (prophase, metaphase, anaphase, and telophase) resulting in two new nuclei, each of which has exactly the same chromosome and DNA content as the original cell. Also called indirect nuclear division, karyokinesis, mitotic division.
The entire process of cell division including division of the nucleus and the cytoplasm.
mitosis (mī-tō'sĭs) Pronunciation Key
(click for larger image in new window) The process in cell division in eukaryotes in which the nucleus divides to produce two new nuclei, each having the same number and type of chromosomes as the original. Prior to mitosis, each chromosome is replicated to form two identical strands (called chromatids). As mitosis begins, the chromosomes line up along the center of the cell by attaching to the fibers of the cell spindle. The pairs of chromatids then separate, each strand of a pair moving to an opposite end of the cell. When a new membrane forms around each of the two groups of chromosomes, division of the nucleus is complete. The four main phases of mitosis are prophase, metaphase, anaphase, and telophase. Compare meiosis. mitotic adjective (mī-tŏt'ĭk) Our Living Language : Mitosis is the process by which the nucleus divides in eukaryotic organisms, producing two new nuclei that are genetically identical to the nucleus of the parent cell. It occurs in cell division carried on by human somatic cells—the cells used for the maintenance and growth of the body. These cells have two paired sets of 23 chromosomes, or 46 chromosomes in total. (Cells with two sets of chromosomes are called diploid.) Before cell division occurs, the genetic material in each chromosome is duplicated as part of the normal functioning of the cell. Each chromosome then consists of two chromatids, identical strands of DNA. When a cell undergoes mitosis, the chromosomes condense into 46 compact bodies. The chromatids then separate, and one chromatid from each of the 46 chromosomes moves to each side of the cell as it prepares to divide. The chromatids form the chromosomes of the daughter cells, so that each new cell has 46 chromosomes, (two complete sets of 23) just like the parent cell. ◇ While both mitosis and meiosis refer properly to types of nuclear division, they are often used as shorthand to refer to the entire processes of cell division themselves. When mitosis and meiosis are used to refer specifically to nuclear division, they are often contrasted with cytokinesis, the division of the cytoplasm. |
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