MITO ITOSI SI SIS S STAGES PROPHASE METHAPHASE ANAPHASE EVENTS/ ACTIVITIES 1. At the onset of mitosis, the nuclear membrane of a cell is intact and as this stage progresses, the nuclear membrane disappears. 2. In the nucleus, chromatin material becomes tightly-coiled as it condenses into discrete chromosomes. 3. The condensed chromosomes appear as two identical sister chromatids united along the centromere or kinetochore. 4. The mitotic spindle in the cytoplasm starts form. 5. Centrioles move away from each other and towards the opposite poles. This is propelled by lengthening bunldes of microtubules found between them. 1. At this stage, the centrioles have finally reached their respective poles. 2. Chromosomes start to assemble at the metaphase plate, an imaginary plane midway between the spindles two poles. The centromeres of all chromosomes are aligned with one another and sister chromatids of each chromosome are assembled at the equator of the cell. 3. The centromeres of the sister chromatids face the opposite pole of the cell. Thus, the identical chromatids of each chromosome are attached to the microtubules radiating from the opposite poles of the cell. The spindle fibers are very abundant during this stage. 1. This starts when paired centromeres of each chromosome separate. This way, the sister chromatids start to move away from each other. Each sister chromatid is now considered a full-fledged chromosome. 2. The sister chromatids then begin to move along the microtubules at the point of attachment- the centromeretoward the opposite pole of the cell. 3. This movement is usually referred to as “the dancing of the chromosomes by some biologist” DIAGRAM MITO ITOSI SI SIS S Telophase 4. By the end of anaphase, two poles of the cell now have an equal and complete set of chromosomes. 1. The daughter nuclei start to form at the two plates of the cell, where the chromosomes have assembled. 2. Nuclear membranes start to reappear are reconstructed from fragments of the cell’s former nuclear envelope. 3. The nucleoli reappear and the chromatin fiber of each chromosomes uncoils. 4. The division of one nucleus into two genetically identical nuclei is now complete. This is followed by cytokinesis, the division of the cytoplasm into two, eventually forming two new daughter cells. This is the last part of mitosis.