Both the eukaryotic and prokaryotic cells have a cell surface membrane and contain cytoplasm and ribosomes. However, eukaryotic cells contain membrane bound organelles, such as mitochondria, nuclei, endoplasmic reticulum and chloroplasts. While both eukaryotic and prokaryotic cells can have a cell wall, in eukaryotic cells the cell wall is made out of cellulose (plants) or chitin (fungi) whilst in prokaryotic cells the cell wall is made out of peptidoglycan. Prokaryotic cells are much smaller than eukaryotic cells, possibly being up to 10 times smaller, also prokaryotic cells do not contain a nucleus, they have free DNA in the cytoplasm that forms circular loops called plasmids.