Somehow the cell knows when all of the chromosomes are lined up at the metaphase
plate. Once all the chromosomes are lined up at the metaphase plate (with the
kinetochores of sister chromatids facing opposite poles) this triggers the next stage -
1. At anaphase the sister chromatids lose the connection in the centromere region as the
cohesions are removed from the centromere region Figure 9.11, page 191, and the polar
wind stops. Once the sister chromatids are no longer attached, each is called a
2. Since sister chromatids are no longer attached to each other, the kinesin motor protein
can now drag the daughter chromosomes to the poles.
Not only do the chromosomes walk to the pole, but the poles move away from each other
and so the chromosomes very quickly separate from each other.
When the chromosomes reach the poles that triggers the last stage of mitosis, telophase.
Telophase is in many ways, the reverse of prophase.
1. During telophase the chromosomes de-condense; they once again become very thin
and very long.
2. The kinetochores dis-assembled.
3. The nucleolus re-assembles.
4. The mitotic spindle dis-assembles.
5. The nuclear envelope re-forms.
You can see all of the stages in a real organism in Figure 9.10, pages 190-191.
In eukaryotes cell division is considered in two parts: (a) division of the nuclear
components and (b) division of the cytoplasmic components.
By the end of mitosis, the division of the nucleus is completed. But cell division is not
complete, the rest of cell division-- division of the cytoplasm and all its components
Separation of the cytoplasmic components of the cell is called cytokinesis.
In animals and single celled prokaryotes without a cell wall, cytokinesis occurs by a
pinching in rather like a balloon being squeezed in half. Figure 9.12a, page 192.
However in plants, fungi and protists with their cell walls another method must be used,
because it is not easy to ‘pinch in’ a wall. Instead a cell plate forms between the two new
cells. This cell plate will organize the new cell wall that will divide the two daughter
cells. Figure 9.12b