A delicate, double membrane-bounded body found within the cytoplasm of most cells of plants and animals, but not bacteria. It contains the chromosomes that can be seen with the aid of a microscope during meiosis and mitosis. It functions as the control center of the cell. The double membrane, or nuclear membrane, contains many pores through which there is an exchange of material between the nucleus and the cytoplasm.
See Cell, Centromere, Chromatin, Chromosome, Cytoplasm, Eukaryote cell (or organism), Karyotyping, Meiosis (or reduction division), Mitosis, Nucleoid, Organelles, Protoplasm