The sites of protein synthesis in the cells of both prokaryotes and eukaryotes are the structures in the cytoplasm called

In both prokaryotic and eukaryotic cells, the sites of protein synthesis are known as ribosomes. Ribosomes are essential molecular machines that translate messenger RNA (mRNA) sequences into polypeptide chains, which will fold into functional proteins.

In prokaryotes, ribosomes float freely in the cytoplasm since these cells lack membrane-bound organelles. In eukaryotic cells, ribosomes can be found either free in the cytoplasm or attached to the endoplasmic reticulum (ER), which is then referred to as the rough ER. This structure allows for the synthesis of proteins destined for secretion or for use within the endomembrane system.

Overall, ribosomes play a critical role in gene expression, serving as the site where the information encoded in mRNA is translated into the amino acid sequences that form proteins.