Cell Nucleus

Part of the eukaryotic cell which contains most of the cell's chromosomes. It is separated from the rest of the cell by the nuclear membrane. This seems to be continuous with a membrane inside the cell called the endoplasmic reticulum, and has pores which probably allow large molecules to move in and out of the nucleus. This is necessary since the messenger RNA which is made in the nucleus has to travel out into the rest of the cell so it can be used to direct the production of protein.