Final answer:
Ribosomes are the universal cellular structures found in both eukaryotic and prokaryotic cells, where they facilitate protein synthesis.
Step-by-step explanation:
The structure found in both eukaryotic and prokaryotic cells is ribosomes. Ribosomes are the sites of protein synthesis and are essential components of all living cells. While eukaryotic cells possess membrane-bound organelles like a true nucleus and mitochondria, prokaryotic cells do not. Instead, prokaryotic cells have a nucleoid region where their DNA is located.
However, both cell types have ribosomes, which may be found floating within the cytoplasm or attached to the cytoplasmic side of the plasma membrane or endoplasmic reticulum. Ribosomes are found in both prokaryotic and eukaryotic cells. Ribosomes play a key role in protein synthesis, which is a vital process for all cells. They are responsible for translating the genetic information from RNA into proteins.