Anaphase 178480 219561091 2008-06-15T20:54:30Z Exothermic 5071973 correct spelling typo "mictrotubules" <!-- see discussion [[Image:Mitosis-flourescent.jpg|thumb|right|300px|A [[lung]] cell of a [[newt]] during early anaphase of mitosis. The cell is [[staining (biology)|stained]] with [[fluorescent]] [[dye]]s. ]]--> [[Image:Anaphase-flourescent.jpg|thumb|right|300px|Newt lung cell during late anaphase. Chromosomes are in blue, the spindle in green.]] '''Anaphase''', from the [[ancient Greek]] ''ανα'' (up) and ''φασις'' (stage), is the stage of [[mitosis]] when [[chromosome]]s separate in a [[eukaryote|eukaryotic]] [[cell (biology)|cell]]. Each [[chromatid]] moves to opposite poles of the cell, the opposite ends of the [[mitotic spindle]], near the [[microtubule organizing center]]s. ==Regulation== Anaphase begins abruptly with the regulated triggering of the metaphase-to-anaphase transition. At this point the [[Anaphase Promoting Complex]] (APC) becomes activated. This terminates [[metaphase]] (M-phase) activity by [[cleave|cleaving]] and inactivating the M-phase cyclin required for the function of M-phase [[cyclin dependent kinases]] (M-Cdks). It also cleaves [[securin]], a protein that inhibits the [[protease]] known as [[separase]]. Separase then cleaves [[cohesin]], a protein responsible for holding sister chromatids together. ==Early and late anaphase== Within anaphase two distinct processes occur. * During '''early anaphase''' (or Anaphase A) the chromatids abruptly separate and move towards the spindle poles. This is achieved by shortening of the spindle microtubules, and forces are mainly exerted at the [[kinetochores]]. * When the chromatids are fully separated '''late anaphase''' (or Anaphase B) begins. This involves the polar microtubules elongating and sliding relative to each other to drive the spindle poles further apart. Anaphase B drives separation of the sister centrosomes to their opposite poles through three forces. Kinesin proteins attached to polar microtubules push the microtubules past one another. A second force involves pulling of the microtubules by cortex-associated cytosolic dynein. The third force for the separation of chromosomes involves lengthening the polar microtubules at the plus end. These two processes were originally distinguished by their different sensitivities to drugs, and mechanically they are distinct processes. * Early anaphase involves shortening kinetochore microtubules by depolymerization at both ends. During this, [[List of gene families#Motor proteins|motor proteins]] at the kinetochores pull on the kinetochore microtubules. * Late anaphase involves both the elongation of overlap microtubules and the use of two distinct sets of motor proteins: one of these pulls overlap microtubules past each other, the other pulls on astral microtubules that have attached to the cell cortex. The contributions of early anaphase and late anaphase to anaphase as a whole vary with cell type. In mammalian cells, late anaphase follows shortly after early anaphase and extends the spindle to around twice its [[metaphase]] length; in contrast [[yeast]] and certain [[protozoa]] use late metaphase as the main means of chromosome separation and can extend the spindle to up to 15 times its metaphase length in the process. {{Cell cycle}} [[Category:Mitosis]] [[de:Mitose#Anaphase]] [[es:Anafase]] [[fr:Anaphase]] [[nl:Anafase]] [[pt:Anáfase]] [[ro:Anafază]]