Eukaryotes have the possibility of being single-celled. Both prokaryotic and eukaryotic cells have common structures. All prokaryote and eukaryote cells have ribosomes, cytoplasm, plasma membrane, and DNA. The plasma membrane, or cell membrane, is the phospholipid layer that surrounds the cell and protects it from the outside environment.
The eukaryotes a cell wall as well, not a prokaryote.