Final answer:
The nucleolus is responsible for assembling ribosomes by aggregating ribosomal RNA with associated proteins. It is a non-membrane bound organelle found within the nucleus of many cells.
Step-by-step explanation:
The nucleolus is a non-membrane bound organelle found within the nucleus of many cells. Its main function is to assemble ribosomes. Ribosomes are organelles made of protein and ribosomal RNA (rRNA), and they are responsible for building cellular proteins in the cytoplasm.
The nucleolus aggregates ribosomal RNA with associated proteins to assemble ribosomal subunits, which are then transported out of the nucleus to the cytoplasm through the pores in the nuclear envelope.