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.

---

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

---

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.

---

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

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

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

If the nucleolus were not able to carry out its function, what other cellular organelles would be affected?

From Textbooks ● Jun. 9, 2022

It is simply a single cell, with some power of amoeboid motion, a single nucleus and nucleolus; and in amphioxus its protoplasm is clear and transparent.

From Text Book of Biology, Part 1: Vertebrata by Wells, H. G. (Herbert George)

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

In tests, the team found that large nucleoli had less stable rDNA than smaller ones.

From Science Daily ● Nov. 25, 2024

This organization gives rise to unique pH profiles within nucleoli, which they measured and compared with the pH of nearby non-nucleolar condensates including nuclear speckles and Cajal bodies.

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

At first no nucleoli are present in the daughter nuclei, but they appear before the division is complete.

From Elements of Structural and Systematic Botany For High Schools and Elementary College Courses by Campbell, Douglas Houghton