What is the difference between a prokaryotic cell and a eukaryotic cell?

Prokaryotic cells are smaller and more simple than eukaryotic cells. They do not contain membrane bound organelles such as mitochondria, endoplasmic reticulum and golgi apparatus. They also do not have a nucleus, instead their DNA is circular and floats freely in the cytoplasm of the cell. Their DNA is also different from eukaryotic cells in that it is not associated with histone proteins. Some prokaryotic cells also have additional DNA to their chromosomal DNA in the form of plasmids which are small circular loops of DNA that can be replicated and passed between cells. Prokaryotic cells do however have some similarities with eukaryotic cells. These include: the presence of a plasma membrane, the presence of ribosomes and the presence of a cell wall (this is not always present in all eukaryotes though).