A centromere is a constricted region of a chromosome that separates it into a short arm (p) and a long arm (q) . It is a specialized DNA sequence in the chromosomes that links or holds together the pair of sister chromatids. During cell division, the centromere plays a key role in helping the cell divide up its DNA by acting as the point of attachment of the kinetochore, a structure to which the microtubules of the mitotic spindle become anchored. Following attachment of the spindle fibers to the centromere, the two identical sister chromatids that make up the replicated chromosome are pulled to opposite sides of the dividing cell, such that the two resulting daughter cells end up with identical DNA.
The centromere is located at the center of the chromosome, which is why it is named using combining forms of centro- and -mere, yielding "central part". The centromere is not always in the middle of the chromosome, and sometimes it can be almost all the way at the top, which is called an "acrocentric chromosome". The centromere is composed of a specific kind of repetitive DNA called "alpha satellite," which is where the proteins that the centromere needs to attach to the spindle fibers come together.
There are different types of centromeres, and this classification is mainly based on the location of the centromere on the chromosomes, which includes metacentric, submetacentric, acrocentric, and telocentric. The centromere is a conserved and essential feature of eukaryotic chromosomes that enables the equal segregation of genetic material into daughter cells during cell division.
