mitosis
Americannoun
-
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.
noun
-
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
-
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.)
Closer Look
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. diamf3 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.
Other Word Forms
- intermitotic adjective
- mitotic adjective
- mitotically adverb
Etymology
Origin of mitosis
First recorded in 1885–90; from Greek mít(os) “thread” + -osis
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
"It's about creating the conditions for the system to run smoothly. CENP-E's key role is to stabilize the start, and once that happens, the rest of mitosis unfolds correctly."
From Science Daily • Dec. 10, 2025
Using a powerful, high-resolution genome mapping method, the team found that small 3D loops -- connections between regulatory DNA elements and genes -- remain intact even during cell division, a stage known as mitosis.
From Science Daily • Oct. 24, 2025
The discovery may also explain a long-observed burst in gene transcription that occurs near the end of mitosis.
From Science Daily • Oct. 24, 2025
Many of these loops allow genes to interact with distant regulatory regions -- sometimes millions of base pairs apart -- while others form during mitosis to pack chromosomes tightly.
From Science Daily • Oct. 24, 2025
The centrioles, which hoist the microtubules on which chromosomes are strung for mitosis, are similar separate creatures; when not busy with mitosis, they become the basal bodies to which cilia are attached.
From "The Lives of a Cell" by Lewis Thomas
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.