The nucleus is a membrane-bounded organelle found in eukaryotic cells that contains the chromosomes and nucleolus. Intact eukaryotic cells are comprised of a nucleus and cytoplasm. A nuclear envelope encloses chromatin, the nucleolus, and a matrix which fills the nuclear space.

The chromatin consists primarily of the genetic material, DNA, and histone proteins. Chromatin is often arranged in fiber like nucleofilaments.

The nucleolus is a globular cell organelle important to ribosome function and protein synthesis. The nucleolus is a small structure within the nucleus that is rich in ribosomal RNA and proteins. The nucleolus disappears and reorganizes during specific phases of cell division. A nucleus may contain from one to several nucleoli. Nucleoli are associated with...