What is the function of the nucleolus?

The nucleolus plays a crucial role in the assembly of ribosomal subunits, which are essential for protein synthesis in the cell. This specialized structure is found within the nucleus and is primarily responsible for synthesizing ribosomal RNA (rRNA) and combining it with proteins to form the two subunits of ribosomes. These ribosomal subunits are then transported out of the nucleus to the cytoplasm, where they combine to form functional ribosomes that carry out the process of translation, converting messenger RNA (mRNA) into proteins.

Understanding this function is fundamental because ribosomes are vital to nearly every cellular process that requires protein synthesis, meaning the nucleolus is integral to cells' overall functioning and growth. This highlights the nucleolus's importance, distinguishing its role from other cellular components associated with protein processing, waste breakdown, or energy production.