Centromere

(redirected from Centromeres)
Also found in: Dictionary, Thesaurus, Medical.

centromere

[′sen·trə‚mir]
(cell and molecular biology)
A specialized chromomere to which the spindle fibers are attached during mitosis. Also known as kinetochore; kinomere; primary constriction.

Centromere

 

a part of a chromosome that plays a fundamental role in its movement during cell division (mitosis). In the metaphase stage of mitosis, the area of the centromere within the chromosome is less dense than the chromosome’s other areas and forms a primary constriction that divides the chromosome into two sections; the position of this constriction is a basis for the classification of chromosomes. The cytoplasmic filaments (microtubules) of the spindle of cell division are attached to the centromere by their ends.

Some organisms, such as members of the genus Luzula and the scorpion, have polycentromeric chromosomes with a diffuse centromere and with the spindle filaments attached to the chromosome along its entire length. With a light microscope a cluster of chromomeres may be seen near the centromere of a chromosome during metaphase. Examination of mammalian cells with an electron microscope reveals a three-layered structure near each of the two longitudinal chromosome filaments, or chromatids. This structure is a kinetochore plate, whose interaction with the spindle filaments results in the even distribution of chromosomes among the daughter cells during cell division. Chromosomal aberrations involving the chromomere hamper the distribution of chromosomal material during mitosis and meiosis and alter the organism’s karyotype. Chromosomes that lack a centromere cannot take part in mitosis.

I. I. KIKNADZE

References in periodicals archive ?
B chromosome nondisjunction in corn: control by factors near the centromere.
Prior to anaphase, the CPC is highly enriched at the inner centromere, and ABK activity contributes to spindle and kinetochore assembly, spindle assembly checkpoint signaling, and error correction (Tanaka et al.
Constitutive heterochromatin regions are found at or around centromeres and telomeres using the C-banding method.
New York University researchers focused on the organization and functioning of the centromere, which is responsible for chromosome segregation--a process that ensures that replicating cells receive a complete copy of the genome.
The former shows reactions to nucleolar RNA and RNA polymerase I, and the latter reacts to centromere (Table 1).
Some remarks on the evolution of the centromere, based upon the distribution of centromere types in insects.
In mice (and also in grasshoppers) it has been shown that one feature of the nuclear architecture of sex cells is that centromeres tend to cluster in vivo in a specific region of the nucleus (Redi & Capanna 1990, Marti & Bidau 2001).
Chromosomes with two centromeres are mitotically unstable.
The centromere is functional, but it isn't wrapped in a blanket of repetitive DNA, suggesting the repetitive elements aren't necessary for a centromere to function.
The functional but evolutionarily immature centromere in the horse may provide a model to study factors responsible for how centromeres function.