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Dark area within the nucleus — identity
publish date: 2026/06/16 20:56:43.334480 UTC
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When the cell is not dividing, there is a conspicuous dark area within the nucleus that contains a high concentration of ribonucleic acid and protein. What is this structure?
Correct Answer
nucleolus
Explanation
The nucleolus is the conspicuous dark area visible within the nucleus of a non-dividing cell. It contains a high concentration of ribonucleic acid (RNA) and protein, and is the site of ribosome production. During mitosis, when chromosomes condense, the nucleolus disappears and ribosome synthesis ceases.
Reference
Biology: A Self-Teaching Guide