a part of the cell containing DNA and RNA and responsible for growth and reproduction any histologically identifiable mass of neural cell bodies in the brain or spinal cord the positively charged dense center of an atom (astronomy) the center of the head of a comet; consists of small solid particles of ice and frozen gas that vaporizes on approaching the sun to form the coma and tail
A discrete structure within the cell that is bounded by a nuclear membrane It contains most of the genetic material of the cell
The massive, positively charged central part of an atom made up of protons and neutrons
An organelle of eukaryotic cells that is bounded by a nuclear membrane and contains the chromosomes whose genes control the structure of proteins within the cell
The central controlling body within a living cell, usually a spherical unit enclosed in a membrane and containing genetic codes for maintaining life systems of the organism and for issuing commands for growth and reproduction
The center of an atom, that contains protons and neutrons and carries a positive charge
(pl nuclei) The center of an atom, consisting of one or more protons and associated neutrons
a membrane-bounded compartment in an eukaryotic cell which contains the genetic material and the nucleoli The nucleus represents the control center of the cell Nuclei divide by mitosis or meiosis
The positively charged core of an atom, consisting of protons and neutrons (except for hydrogen), around which electrons orbit