Transcript: There are two fundamentally different types of cells in life on Earth: prokaryotes and eukaryotes. The prokaryotes are cells without nuclei. They are ten times smaller then the eukaryotes, and they are far less complex in a chemical sense. Eukaryotes, which are larger, have their DNA contained in a nucleus which provides a higher level of functioning and complexity. Examples of prokaryotes are E coli and salmonella. Examples of eukaryotes are amoeba and of course the trillions and trillions of cells in our own bodies. Prokaryotes evolved first and lead to eukaryotes, but both are essential for life on Earth. Although we are more familiar with material that includes cells with nuclei, there are more examples of prokaryotic organisms on Earth than there are eukaryotes, and the small organisms like bacteria are essential to the functioning of the higher level organisms. The reverse is not true. Prokaryotes could exist quite happily without the existence of cells with nuclei.