What is the primary function of the nucleolus in a cell?

The primary function of the nucleolus in a cell is to manufacture ribosomes. The nucleolus is a specialized structure found within the nucleus and is primarily involved in the synthesis of ribosomal RNA (rRNA), which is a key component of ribosomes. Ribosomes are essential for protein synthesis, as they translate messenger RNA (mRNA) into proteins by assembling amino acids in the appropriate sequences. The nucleolus not only contributes to the production of rRNA but also helps in assembling rRNA with proteins to form the subunits of ribosomes, which are then exported to the cytoplasm for their role in protein synthesis. Understanding the function of the nucleolus is critical in cellular biology, as it underlines the intricate processes involved in gene expression and the overall functioning of the cell.