There are two main kinds of cells: prokaryotic and eukaryotic. Prokaryotic cells have only a few parts. Their DNA is the shape of a circle, inside the cytoplasm, and they have no membranes inside the cell. Eukaryotic cells are more complex, and they have a cell nucleus. The DNA is inside the nucleus, and a membrane is around the nucleus. Eukaryotic cells also have other parts, called organelles. Some of these other organelles also have membranes.