There are four organelles found in eukaryotic cells that aid in the synthesis of proteins. These organelles include the nucleus, the ribosomes, the rough endoplasmic reticulum and the Golgi apparatus. All of these organelles help produce and process proteins, but only the ribosomes actually piece together amino acids into proteins.
Ribosomes can be free-floating in the cell or attached to other organelles, such as the rough endoplasmic reticulum. These organelles receive RNA from the cell's nucleus and transcribe and translate the RNA into amino acids. The ribosome then assembles the amino acids into chains. Amino acid chains are also known as proteins. These proteins can then be transported to the rough endoplasmic reticulum and the Golgi apparatus for further synthesis and processing.