nucleolus

[noo-klee-uh-luhs, nyoo-]

noun

Cell Biology.

plural

nucleoli 

1. a conspicuous, rounded body within the nucleus of a cell.

nucleolus

/ ˌnjuːklɪˈəʊləs /

noun

1. Also called: nucleole. a small rounded body within a resting nucleus that contains RNA and proteins and is involved in the production of ribosomes

nucleolus

plural

nucleoli 

1. A small, typically spherical granular body located in the nucleus of a eukaryotic cell, composed largely of protein and RNA. When the cell is not undergoing division, loops of DNA from one or more chromosomes extend into the nucleolus and direct the synthesis of ribosomal RNA and the formation of ribosomes. The ribosomes are eventually transferred out of the nucleus via pores in the nuclear envelope into the cytoplasm.

Other Word Forms

• nucleolar adjective

Word History and Origins

Origin of nucleolus¹

1835–45; < Late Latin: small kernel, equivalent to nucle ( us ) kernel ( nucleus ) + -olus -ole ¹

Word History and Origins

Origin of nucleolus¹

C19: from Latin, diminutive of _nucleus

Example Sentences

The secret to cellular youth may depend on keeping the nucleolus -- a condensed structure inside the nucleus of a cell -- small, according to Weill Cornell Medicine investigators.

From Science Daily

This caused RAG1 to get trapped within cell nucleoli instead of facilitating the gene rearrangements that build immune diversity.

From Science Daily

The nucleolus is a prominent condensate in cells.

From Science Daily

All of these stubby arms huddle together to form a structure called the nucleolus, in which DNA is transcribed into ribosomal RNA, which then folds into the ribosomal machinery that makes proteins.

From Science Daily

All eukaryotes have the exact same set of organelles familiar to anyone who has studied cell biology: nucleus, nucleolus, ribosomes, rough and smooth endoplasmic reticulum, Golgi apparatus, cytoskeleton, lysosome and centriole.

From Scientific American