only_in_taxon only in taxon in taxon nucleus horsetail nucleus A membrane-bounded organelle of eukaryotic cells in which chromosomes are housed and replicated. In most cells, the nucleus contains all of the cell's chromosomes except the organellar chromosomes, and is the site of RNA synthesis and processing. In some species, or in specialized cell types, RNA metabolism or DNA replication may be absent. Wikipedia:Cell_nucleus cell nucleus NIF_Subcellular:sao1702920020 cellular_component GO:0005634 intracellular membrane-bounded organelle Eukaryota