nucleolus

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

noun

, Cell Biology.

, plural nu·cle·o·li [noo-, klee, -, uh, -lahy, nyoo-].

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

nucleolus

/ ˌnjuːklɪˈəʊləs /

noun

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

nucleolus

/ no̅o̅-klē′ə-ləs /

, Plural nucleoli no̅o̅-klē′ə-lī′

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.

Derived Forms

• ˌnucleˈolar, 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

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

Yet many other well-known cellular structures, including the nucleolus—an organelle within the nucleus—and the RNA-processing Cajal bodies, lack membranes.

From Science Magazine