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

In fact, if they lowered the concentration below a critical threshold, there was no phase separation and no nucleolus.

From Quanta Magazine

Their granular nucleus is rounded or oval, and typically contains a single nucleolus.

From Project Gutenberg

Each of them has a large nucleus, with a deeply staining small nucleolus, and a very scanty protoplasm.

From Project Gutenberg

I have very rarely met with the condition with the single nucleolus described by Schultz in Torpedo.

From Project Gutenberg

In anucleate cells there is probably only a single process of layer formation round an infinitely small nucleolus.

From Project Gutenberg

And within this nucleus is often to be seen another smaller body, frequently appearing as a mere dot, called the nucleolus.

From Project Gutenberg