What is the main role of the cell's nucleus?

The main role of the cell's nucleus is the storage of genetic material, which is primarily in the form of DNA. Within the nucleus, the DNA is organized into structures known as chromosomes. This genetic material contains the instructions necessary for the growth, development, functioning, and reproduction of the organism. The nucleus also plays a crucial role in regulating gene expression and mediating the replication of DNA during the cell cycle.

While energy production, protein synthesis, and photosynthesis are all vital cellular processes, they do not occur directly within the nucleus. Energy production happens in organelles such as mitochondria; protein synthesis primarily takes place in the ribosomes, often with the help of messenger RNA that is transcribed from DNA in the nucleus; and photosynthesis occurs in chloroplasts, which are present in plant cells. Hence, the nucleus stands out for its specific and essential function in safeguarding and managing the cell's genetic blueprint.