What is the function of the nucleus in a cell?

The nucleus serves a vital role in the cell by housing the genetic material, which is organized into DNA within the chromosomes. This genetic material contains the instructions necessary for the development, functioning, and reproduction of the organism. The nucleus also plays a crucial role in controlling the cell's activities by regulating gene expression, which in turn influences protein synthesis and various cellular processes. By coordinating these activities, the nucleus ensures that the cell operates efficiently and responds appropriately to its environment.

In contrast, other functions attributed to different organelles or cellular structures clarify why they do not pertain to the nucleus. For instance, protein synthesis occurs primarily in the ribosomes; energy storage typically involves structures like vacuoles or mitochondria; and while the nucleus does play a part in cell division through the mitosis process, it is not its primary function, which is fundamentally linked to genetic material and overall cellular control.