The part of the cell that makes protein is the ribosome.

Here's a breakdown of the process:

1. DNA in the nucleus contains the genetic instructions for making proteins.

2. A copy of the DNA instructions, called mRNA, is created.

3. mRNA travels out of the nucleus and into the cytoplasm.

4. Ribosomes, found in the cytoplasm, attach to the mRNA.

5. Ribosomes read the mRNA instructions and use them to assemble amino acids into a chain, forming a protein.

So, while the nucleus holds the blueprints, the ribosomes are the actual construction workers building the proteins.