Proteins are synthesized inside the cell primarily at the ribosomes. Ribosomes are complex molecular machines composed of ribosomal RNA and proteins that translate the genetic code carried by messenger RNA (mRNA) into a specific sequence of amino acids, forming a polypeptide chain that folds into a functional protein

. In eukaryotic cells, ribosomes can be found in two main locations:

• Free-floating in the cytoplasm , where they synthesize proteins that generally function within the cytosol.
• Attached to the rough endoplasmic reticulum (RER) , where they produce proteins destined for secretion, membrane insertion, or lysosomal targeting

The process begins with transcription in the nucleus, where DNA is transcribed into mRNA. The mRNA then exits the nucleus and binds to ribosomes in the cytoplasm or on the RER to initiate translation, the actual protein synthesis step

. Thus, the ribosome is the cellular site of protein synthesis, operating either freely in the cytoplasm or bound to the rough endoplasmic reticulum in eukaryotic cells