The nucleus of a bacterial cell is not as well-organized as that of a multicellular organism's cell. The nuclear membrane does not exist. Prokaryotic cells have nuclear components but no nuclear membrane. Organisms containing these types of cells are known as prokaryotes. Bacteria and blue-green algae are examples. Eukaryotic cells have a well-organized nucleus with a nuclear membrane. Eukaryotes are all organisms that are neither bacteria nor blue-green algae.