Here's why:

* The nucleus is the control center of the cell: It contains the genetic information (DNA) that directs all the cell's activities.

* DNA is organized into chromosomes: Within the nucleus, DNA is tightly packed and organized into structures called chromosomes.

* Mitochondria also have DNA: While most of a cell's DNA is in the nucleus, there's also a small amount of DNA found in the mitochondria, which are organelles responsible for energy production. This mitochondrial DNA is separate from the nuclear DNA.