Here's the breakdown:

* Nucleus: Contains DNA, the blueprint for building proteins.

* Ribosomes: The cellular machinery that translates the DNA blueprint into proteins.

* Nucleolus: A specialized region within the nucleus where ribosomes are assembled.

The process of ribosome synthesis is as follows:

1. Transcription: DNA is copied into RNA (specifically, ribosomal RNA or rRNA) in the nucleus.

2. Assembly: The rRNA molecules, along with ribosomal proteins, are assembled into ribosomes within the nucleolus.

3. Export: Completed ribosomes are transported out of the nucleus through nuclear pores and into the cytoplasm, where they can translate mRNA into proteins.

So, while the nucleus houses the DNA that contains the instructions for building ribosomes, the actual creation of these structures occurs in the nucleolus, a specialized region within the nucleus.