Here's why:

* Mitosis and Meiosis focus on chromosomes: Both processes are primarily concerned with the accurate separation and distribution of chromosomes, which reside within the nucleus.

* Cytokinesis follows nuclear division: While mitosis and meiosis involve nuclear division, they are often followed by cytokinesis, which is the division of the cytoplasm. However, cytokinesis is a separate process, not directly part of mitosis or meiosis.

Therefore, while the entire cell ultimately divides during these processes, the core focus of mitosis and meiosis is on the division of the nucleus and its chromosomes.