NCI Dictionary of Cancer Terms

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The NCI Dictionary of Cancer Terms features 7,777 terms related to cancer and medicine.

Browse the dictionary by selecting a letter of the alphabet or by entering a cancer-related word or phrase in the search box.

nucleus
(NOO-klee-us)
In biology, the structure in a cell that contains the chromosomes. The nucleus has a membrane around it, and is where RNA is made from the DNA in the chromosomes.

EnlargeDrawing showing a cell containing organelles, including the nucleus (contains DNA), the nucleolus, Golgi complex, mitochondria, and endoplasmic reticulum. Also shown are the cell membrane and a membrane receptor.

Parts of a cell. A cell is surrounded by a membrane, which has receptors on the surface. A cell has several small structures inside it, including the nucleus, mitochondria, endoplasmic reticulum, and Golgi complex. These all have specific functions in the cell.