mi·to·sis
Audio Help [mahy-toh-sis] Pronunciation Key
Audio Help [mahy-toh-sis] Pronunciation Key –noun Cell Biology.
| 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. |
| Dictionary.com Unabridged (v 1.1) Based on the Random House Unabridged Dictionary, © Random House, Inc. 2006. |
mitosis
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mi·to·sis
Audio Help (mī-tō'sĭs) Pronunciation Key
(click for larger image in new window) n. pl. mi·to·ses (-sēz) Biology
[Greek mitos, warp thread + -osis.] mi·tot'ic (-tŏt'ĭk) adj., mi·tot'i·cal·ly adv. |
| The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2006 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved. |
mitosis
1887, coined from Gk. mitos "warp thread" (see miter (1)) + Mod.L. -osis "act, process." Term introduced by Ger. anatomist Walther Fleming (1843-1905) in 1882. So called because chromatin of the cell nucleus appears as long threads in the first stages.
| Online Etymology Dictionary, © 2001 Douglas Harper |
| mitosis | |
noun | |
| cell division in which the nucleus divides into nuclei containing the same number of chromosomes |
| WordNet® 3.0, © 2006 by Princeton University. |
mitosis
Audio Help (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. |
| The American Heritage® Science Dictionary Copyright © 2002 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved. |
mitosis [(meye-toh-sis)]
Division of a single cell into two identical “daughter” cells. Each daughter cell has an identical number of chromosomes as the parent cell. Mitosis begins when the DNA in the parent cell replicates itself; it ends with two cells having the same genes (see genetics). Most cells in the human body, and all single-celled organisms, reproduce through mitosis. (Compare meiosis.)
[Chapter:] Life Sciences
| The American Heritage® New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved. |
mitosis
Kar"y*o*ki*ne`sis\, n. [NL., fr. Gr. ? a nut, kernel + ? to move.] (Biol.) The indirect division of cells in which, prior to division of the cell protoplasm, complicated changes take place in the nucleus, attended with movement of the nuclear fibrils; -- opposed to karyostenosis. The nucleus becomes enlarged and convoluted, and finally the threads are separated into two groups which ultimately become disconnected and constitute the daughter nuclei. Called also mitosis. See Cell development, under Cell.| Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc. |
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