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Subject - cell biology, genetics

Centromeres are nonconserved DNA sequence domains on chromosomes to which the mitotic or meiotic spindles attach (kinetochore formation). Centromeres divide the chromosomes into two arms that are usually of different length and are also known as the p and q arms (linguistic derivation: greek γεντρον/kentron "middle, midpoint"; μεροσ/meros "part"). The two chromatids of a duplicated chromosome are attached at these sequence segments.

The function of these DNA regions is to ensure correct pairing of homologous chromosomes. In addition, they are involved in controlling gene expression. Defective function of the centromere can lead to incorrect placements and separations of the chromosome, which in turn can cause aneuploidy (deviation from a "normal" set of chromosomes), such as trisomy 21 or monosomy 21.

See also: chromosomes