 At a certain point during the cell cycle in open mitosis , the cell divides to form two cells . In order for this process to be possible , each of the new daughter cells must have a full set of genes , a process requiring replication of the chromosomes as well as segregation of the separate sets . This occurs by the replicated chromosomes , the sister chromatids , attaching to microtubules , which in turn are attached to different centrosomes . The sister chromatids can then be pulled to separate locations in the cell . In many cells , the centrosome is located in the cytoplasm , outside the nucleus ; the microtubules would be unable to attach to the chromatids in the presence of the nuclear envelope . Therefore , the early stages in the cell cycle , beginning in prophase and until around prometaphase , the nuclear membrane is dismantled . Likewise , during the same period , the nuclear lamina is also disassembled , a process regulated by phosphorylation of the lamins by protein kinases such as the CDC2 protein kinase . Towards the end of the cell cycle , the nuclear membrane is reformed , and around the same time , the nuclear lamina are reassembled by dephosphorylating the lamins . 
 At a certain point during the cell cycle in open mitosis , the cell <a href='uninflect' title='1'><mark>divides</mark></a> to form two cells . In order for this process to be possible , each of the new daughter cells must have a full set of genes , a process requiring replication of the chromosomes as well as segregation of the separate sets . This <a href='uninflect' title='2'><mark>occurs</mark></a> by the replicated chromosomes , the sister chromatids , attaching to microtubules , which in turn are attached to different centrosomes . The sister chromatids can then be pulled to separate locations in the cell . In many cells , the centrosome is located in the cytoplasm , outside the nucleus ; the microtubules would be unable to attach to the chromatids in the presence of the nuclear envelope . Therefore , the early stages in the cell cycle , beginning in prophase and until around prometaphase , the nuclear membrane is dismantled . Likewise , during the same period , the nuclear lamina <a href='drop_aux' title='3'><mark>is</mark></a>also disassembled , a process regulated by phosphorylation of the lamins by protein kinases such as the CDC2 protein kinase . Towards the end of the cell cycle , the nuclear membrane is reformed , and around the same time , the nuclear lamina are reassembled by dephosphorylating the lamins . 
At a certain point during da cell cycle in open mitosis , tdacell divide to form 2 cells . In order fir dis process to be possible , each of the new daughter cells must have a full set of genes , a process requiring replication of the chromosomes as well as segregation of thdaeparate sets . This occur by the replicated chromosomes , thedaster chromatids , attaching to microtubules , which in turn are attached to diff centrosomes . The sister chromatids can then be pulled to separate locations in the cell . In many cells , the centrosome is located in the cytoplasm , outside the nucleus ; the darotubules would b unable to attach to the chromatids in the pdaence of the nuclear envelope . Therefore , the eada stages in the celdaycle , beginning in prophase and untill around prometaphase , the nuclear membrane is dismantled . Likewise , during the samedariod , the nucledalamina also disassembled , a process regulated by phosphorylation of the lamins by protein kinases such as the CDC2 protein kinase . Towards the end ofdae cell cyda , the nuclear dabrane is reformed , and around the same time , the nuclear lamina are reassembled by dephosphorylating the lamins .