nucleolus
noun
nu·cle·o·lus
nü-ˈklē-ə-ləs 
nyü-
plural nucleoli
nü-ˈklē-ə-ˌlī
nyü-
: a spherical body of the nucleus of most eukaryotes that becomes enlarged during protein synthesis, is associated with a nucleolus organizer, and contains the DNA templates for ribosomal RNA see cell illustration
Examples of nucleolus in a Sentence
Recent Examples on the Web
But at the time Wagner and Valentin had little idea of the nucleolus’s function.
—
Trevor Grandpre, Scientific American, 14 Aug. 2024
Still other types of ncRNAs, called small nucleolar RNAs, work within cell compartments called nucleoli to help modify the RNA in ribosomes—a cell’s protein-making factories—as well as transfer RNA and mRNA.
—Philip Ball, Scientific American, 14 May 2024
In 2019 in Non-Coding RNA, Weber and a co-author weighed the support for phase separation in the cell nucleus and concluded that solid data back its role in forming three structures, including the nucleolus, but not two other structures commonly attributed to the process.
—Mitch Leslie, Science | AAAS, 21 Jan. 2021
In 2012, Brangwynne and colleagues saw similar fluid features in the nucleolus, a dense mix of proteins, RNA, and DNA that manufactures ribosomes, the cell’s protein factories.
—Mitch Leslie, Science | AAAS, 21 Jan. 2021
More membraneless structures continued to be found, such as the nucleolus, a dense structure in the cell nucleus.
—Quanta Magazine, 26 Nov. 2018
But there’s more to the nucleolus than just making ribosomes.
—Joanna Klein, New York Times, 20 May 2018
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Trevor Grandpre, Scientific American, 14 Aug. 2024
Still other types of ncRNAs, called small nucleolar RNAs, work within cell compartments called nucleoli to help modify the RNA in ribosomes—a cell’s protein-making factories—as well as transfer RNA and mRNA.
—Philip Ball, Scientific American, 14 May 2024
In 2019 in Non-Coding RNA, Weber and a co-author weighed the support for phase separation in the cell nucleus and concluded that solid data back its role in forming three structures, including the nucleolus, but not two other structures commonly attributed to the process.
—Mitch Leslie, Science | AAAS, 21 Jan. 2021
In 2012, Brangwynne and colleagues saw similar fluid features in the nucleolus, a dense mix of proteins, RNA, and DNA that manufactures ribosomes, the cell’s protein factories.
—Mitch Leslie, Science | AAAS, 21 Jan. 2021
More membraneless structures continued to be found, such as the nucleolus, a dense structure in the cell nucleus.
—Quanta Magazine, 26 Nov. 2018
But there’s more to the nucleolus than just making ribosomes.
—Joanna Klein, New York Times, 20 May 2018
Cite this Entry
“Nucleolus.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/nucleolus. Accessed 10 Jul. 2025.
Copy CitationKids Definition
nucleolus
noun
nu·cle·o·lus
n(y)ü-ˈklē-ə-ləs
plural nucleoli
-ˌlī
: a sphere-shaped body in the cell nucleus that is associated with a particular part of a chromosome, and is rich in ribosomal RNA
Medical Definition
nucleolus
noun
nu·cle·o·lus
n(y)ü-ˈklē-ə-ləs
plural nucleoli
-ˌlī
: a spherical body of the nucleus of most eukaryotes that becomes enlarged during protein synthesis, is associated with a nucleolus organizer, and contains the DNA templates for ribosomal RNA
called also plasmosome
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