41. The cell cycle surveillance mechanism that prevents sister-chromatid separation and transition into anaphase is called the spindle checkpoint. 42. Geminin was originally identified as an inhibitor of DNA replication and substrate of the anaphase promoting complex ( APC ). 43. Moreover, survivin has been shown to localize to components of the mitotic spindle during metaphase and anaphase of mitosis. 44. This regulatory role may be directly associated with the role of topoisomerase II in disjoining sister chromatids prior to anaphase . 45. As one of the checkpoint proteins, Bub3 delays the irreversible onset of anaphase through direction of kinetochore localization during prometaphase 46. The encoded protein localizes to prophase kinetochores before ZW10 does and it remains detectable on the kinetochore until late anaphase . 47. Concurrently, anaphase -promoting complex ( APC ) activity decreases significantly, allowing S and M cyclins to become activated. 48. Genetic mosaicism can result from many different mechanisms including chromosome non-disjunction, anaphase lag and endoreplication . [ 1] 49. Microtubule attachment at all of the kinetochore binding sites is not necessary for deactivation of the SAC and progression to anaphase . 50. Monopolin is required for the segregation of homologous centromeres to opposite poles of a dividing cell during anaphase I of meiosis.
