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Centromere

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Definition

noun, plural: centromeres

The dense, constricted region containing highly-specialized repetitive DNA sequence, and functions chiefly by joining the two sister chromatids that make up the X-shaped chromosome and by serving as a site for kinetochore assembly during cell division


Supplement

Centromere is the dense, constricted region where kinetochore is assembled. It contains highly-specialized repetitive DNA sequence (e.g. satellite DNA) of a chromosome linking sister chromatids forming a dyad. Most eukaryotes have DNA sequences in their centromere that are packaged into heterochromatin.

The centromere also serves as a site for kinetochore assembly. Kinetochore is important as it is where spindle fibers attach to during cellular division. Thus, centromere is essential in this regard. Aside from being the region where chromatids are held, it also serves as the point of attachment for spindle fibers (via kinetochore) especially when the spindle fibers are pulling the chromosomes apart toward the centrioles (situated on opposite poles in a cell). This pulling event is observed during anaphase prior to cytokinesis. When the centromere is not functioning properly, the chromatids would not be able to align and separate properly, thus, resulting in the wrong number of chromosomes in the daughter cells, and conditions such as Down syndrome.

The position of the centromere in the chromosome results in the characterization of the chromosomal arms. The chromosomal arm that is shorter is called p whereas the longer arm is called q.

Based on the position of the centromere, the chromosomes may be classified as metacentric, submetacentric, acrocentric, telocentric, subtelocentric, and holocentric.


Word origin: Latin centrum, Greek kentron + meros ("part")

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Related term(s):

Related form(s):

  • centromeric (adjective, of, or pertaining to, the centromere)