- The cellular organelle in eukaryotes that contains most of the genetic material.
Definition from: Human Genome Project Information
at the U.S. Department of Energy
- A nucleus is a membrane-bound organelle that contains the cell's chromosomes. Pores in the nuclear membrane allow for the passage of molecules in and out of the nucleus.
Definition from: Talking Glossary of Genetic Terms from the National Human Genome Research Institute
Related discussion in the Handbook
See also Understanding Medical Terminology.