Here's why:

* Nucleus: The nucleus is the control center of the cell and houses the genetic material (DNA) in the form of chromosomes. Mitosis involves the duplication and separation of these chromosomes.

* Other organelles: While other organelles are involved in the process of cell division (like the cytoplasm and the cytoskeleton), the actual division of the chromosomes takes place within the nucleus.

Let me know if you have any other questions about mitosis!