nucleolus

American  

[noo-klee-uh-luhs, nyoo-] / nuˈkli ə ləs, nju- /

noun

Cell Biology.

• nucleoli
  plural

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

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nucleolus British  

/ 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

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nucleolus Scientific  

/ no̅o̅-klē′ə-ləs /

• nucleoli
  plural

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.

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Other Word Forms

Derived Forms

• nucleolar
  adjective

Inflected Forms

Nouns

• nucleoli
  plural

Etymology

Origin of nucleolus

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

Explanation

A nucleolus is the largest structure within the nucleus of a eukaryotic cell. It's the job of a nucleolus to make RNA and ribosomes. In a eukaryote, a cell whose nucleus is contained within a membrane, the nucleolus plays a vital role. It's here that ribosomes, tiny cell machines that produce important proteins, are made. RNA — which works by taking the information in DNA and translating it into proteins — also comes from the nucleolus. Nucleolus basically means "smaller nucleus," from a Latin word meaning "little nut."

Example Sentences

See Examples For:

nucleolus nucleoli

Also, when the structure is large, proteins and other factors that are usually excluded from the nucleolus are no longer kept out.

From Science Daily ● Nov. 25, 2024

It's as if the nucleolus becomes leaky, letting in molecules that can wreak havoc on the fragile rDNA.

From Science Daily ● Nov. 25, 2024

The researchers discovered that tethering the nucleolus was enough to keep it compact, and small nucleoli delayed aging to about the same extent as calorie restriction.

From Science Daily ● Nov. 25, 2024

Pre-rRNAs are transcribed, processed, and assembled into ribosomes in the nucleolus.

From Textbooks ● Jun. 9, 2022

This nucleus may in its turn contain a nucleolus.

From The Mechanism of Life by Stéphane Leduc

The researchers discovered that tethering the nucleolus was enough to keep it compact, and small nucleoli delayed aging to about the same extent as calorie restriction.

From Science Daily ● Nov. 25, 2024

Interestingly, nucleoli did not expand at the same rate during the entire lifespan as cells aged.

From Science Daily ● Nov. 25, 2024

The community of molecules that come together enables emergent properties in the condensates, like internal pH in nucleoli.

From Science Daily ● Mar. 18, 2024

The nucleus contains one or more nucleoli, which serve as sites for ribosome synthesis.

From Textbooks ● Jun. 19, 2013

Partial rest stage between first and second maturation divisions, two nucleoli present.

From Studies in Spermatogenesis Part I by Nettie Maria Stevens