Definition

1. Noun:
   • A small, dense, spherical structure within the nucleus of a cell: The nucleolus is a non-membrane-bound organelle composed of proteins and nucleic acids, primarily involved in the production and assembly of ribosomal components.

Usage

• The term "nucleolus" is used in the context of cell biology and genetics. It refers specifically to a distinct region inside the cell nucleus. It is a singular noun; its plural form is "nucleoli."

Examples

• Noun:
  • The nucleolus is the site of ribosome assembly.
  • Under a microscope, the nucleolus appears as a dark spot within the nucleus.
  • Changes in nucleolar size can indicate the metabolic activity of a cell.

Advanced Usage

• "Nucleolar organizer region": A specific part of a chromosome that contains the genes for ribosomal RNA and around which the nucleolus forms.
  • The nucleolar organizer regions are crucial for forming the nucleolus.

Variants and Related Words

• Nucleolar (adj): Pertaining to or of the nature of a nucleolus.
  • Nucleolar proteins are essential for its function.
• Nucleoli (n, plural): The plural form of nucleolus.
  • The cell contained two prominent nucleoli.

Synonyms

• Nuclear body (a more general term for structures within the nucleus).
• Ribosome factory (a descriptive, non-technical synonym emphasizing its primary function).

Related Phrases

• Nucleolus-associated chromatin: Chromatin that is in contact with or surrounding the nucleolus.
• Nucleolar stress: A cellular response to disruptions in nucleolar function, often linked to disease.

Noun

1. a small round body of protein in a cell nucleus; such organelles contain RNA and are involved in protein synthesis