Definition :
Cell division is
the process by which a parent cell divides into two or more daughter
cells.Cell division usually occurs as part of a larger cell cycle. In eukaryotes,
there are two distinct type of cell division: a vegetative division,
whereby each daughter cell is genetically identical to the parent cell
(mitosis), and a reductive cell division, whereby the number of
chromosomes in the daughter cells is reduced by half, to produce haploid
gametes (meiosis). Both of these cell division cycles are required in
sexually reproducing organisms at some point in their life cycle, and
both are believed to be present in the last eukaryotic common ancestor Prokaryotes
also undergo a vegetative cell division known as binary fission, where
their genetic material is segregated equally into two daughter cells.
All cell divisions, regardless of organism, are preceded by a single
round of DNA replication.
For simple unicellular organisms such as the amoeba, one cell
division is equivalent to reproduction – an entire new organism is
created. On a larger scale, mitotic cell division can create progeny
from multicellular organisms, such as plants that grow
from cuttings. Cell division also enables sexually reproducing organisms
to develop from the one-celled zygote, which itself was produced by
cell division from gametes. And after growth, cell division allows for
continual construction and repair of the organism. A human being's body
experiences about 10,000 trillion cell divisions in a lifetime.
Cell division has been modeled by finite subdivision rules.
The
primary concern of cell division is the maintenance of the original
cell's genome. Before division can occur, the genomic information that
is stored in chromosomes must be replicated, and the duplicated genome
must be separated cleanly between cells. A great deal of cellular
infrastructure is involved in keeping genomic information consistent
between "generations".
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