What is the main role of the nucleus in a cell?

The primary role of the nucleus in a cell is to serve as the storage center for genetic material, specifically DNA. It houses the cell's genetic information, which is crucial for various cellular functions, including growth, reproduction, and metabolism. The DNA within the nucleus contains the instructions needed for the synthesis of proteins, which are essential for numerous cellular processes. Additionally, the nucleus is involved in the regulation of gene expression, ensuring that the right proteins are produced at the right times in response to the cell's needs.

While protein production and energy production are important cellular functions, they occur in different parts of the cell, such as the ribosomes and mitochondria, respectively. Similarly, waste management is managed by structures like lysosomes and the cell membrane, rather than being a function of the nucleus. Thus, the discernible primary function of the nucleus is its critical role in storing and managing genetic information.