Final answer:
The nucleolus in a typical non-dividing nucleus is responsible for synthesizing ribosomal RNA (rRNA) and assembling ribosomal subunits, which are essential for protein synthesis in the cell.
Step-by-step explanation:
The Nucleolus: A Hub for Ribosome Assembly
In a non-dividing nucleus, the nucleolus functions primarily as the site for ribosomal RNA (rRNA) synthesis and the assembly of ribosome subunits. This dense region found within the nucleus is key to the production of ribosomes, which are critical for protein synthesis within the cell. The nucleolus aggregates the rRNA with associated proteins to form the ribosomal subunits that later travel out of the nucleus through the nuclear pores into the cytoplasm, where they become functional ribosomes and direct the synthesis of proteins.