Here's the breakdown:

* Ribosomes are the protein synthesis machinery of the cell.

* Nucleus is the control center of the cell and contains the genetic material (DNA).

* Ribosomal RNA (rRNA), a key component of ribosomes, is transcribed from DNA within the nucleus.

* The rRNA then combines with proteins, also produced in the nucleus, to form the ribosomal subunits.

* These subunits are then transported out of the nucleus into the cytoplasm, where they join together to become functional ribosomes.

So, while ribosomes are active in the cytoplasm, they are initially assembled within the nucleus.