The organelle that contains instructions for making proteins is the nucleus.

Here's why:

* DNA: The nucleus houses the cell's DNA, which contains the genetic code for all the proteins the cell needs.

* Transcription: DNA's instructions are transcribed into messenger RNA (mRNA) within the nucleus.

* mRNA: mRNA carries the genetic code out of the nucleus to the ribosomes.

* Translation: Ribosomes use the mRNA instructions to assemble amino acids into proteins.

So, while ribosomes are the sites of protein synthesis, the nucleus provides the blueprint for protein production.