During mitosis, several key processes take place that ensure the accurate division of a cell’s genetic material. However, one option listed does not pertain to the events of mitosis itself.
1. Condensation of the chromosomes: This occurs during prophase when chromosomes become more compact, making them easier to separate later on.
2. Replication of the DNA: This process actually takes place during the S phase of interphase, prior to mitosis beginning. Therefore, it does not occur during mitosis.
3. Separation of sister chromatids: This is one of the primary functions of mitosis, which occurs during anaphase when the sister chromatids are pulled apart to opposite poles of the cell.
4. Spindle formation: This occurs as the mitotic spindle is assembled during prophase to facilitate the movement of chromosomes.
5. Separation of the spindle poles: During mitosis, especially in anaphase and telophase, the spindle poles are involved in the movement of chromosomes and eventually assist in separating the two daughter cells.
In conclusion, the correct answer is 2. Replication of the DNA, as this event occurs before mitosis rather than during it.