A functional centromere is formed by a chromosomal domain that very often, but not always, is recognizable by a primary constriction in metaphasic chromosomes. It is associated with a kinetochore through which a link is established with the microtubules, which pull the sister chromatids toward the poles of the two daughter cells during cell division. Centromeres therefore mediate chromosome segregation during mitosis and meiosis, but in ways that are relatively different. For instance, binding of the two sister chromatids is normally destroyed at anaphase in mitosis whereas binding is maintained in meiosis all along the first division until anaphase of the second is reached. The same locus is, however, in charge of the two distinct processes.