More than ten years later, Rudolf Virchow, proposed the third idea or belief of the cell theory. All cells arise from preexisting cells. All cells are either prokaryotic or eukaryotic. Prokaryotic cells are bacteria and eukaryotic cells make up all other organisms. They are distinguishable by the types of organelles or internal structures they contain.
Eukaryotic cells are larger and more complex.
Prokaryotes are smaller and do not have a true nucleus. The genetic material floats freely in the cytoplasm of the cell. A plasma membrane surrounds both eukaryotic and prokaryotic cells. Prokaryotes are thought to be the most primitive type of cell. Cells come in a variety of shapes and sizes, ranging from a tiny bacterial cell to a large nerve cell extending between two body parts.