Toggle the table of contents
From Wikipedia, the free encyclopedia
Look up nucleus in Wiktionary, the free dictionary.
Nucleus (PL: nuclei) is a Latin word for the seed inside a fruit. It most often refers to:
- Atomic nucleus, the very dense central region of an atom
- Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell’s DNA
Nucleus may also refer to:
Science, technology, and mathematics[edit]
Astronomy[edit]
- Active galactic nucleus in astronomy
- Comet nucleus, the solid, central part of a comet
Biology[edit]
- Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell’s DNA
- Nucleus (neuroanatomy), a cluster of cell bodies of neurons in the central nervous system
- Nucleus that forms in the eye in nuclear sclerosis (early cataracts)
- Nucleus, a scientific journal concerned with the cell nucleus; published by Taylor & Francis
- Nucleus, a small colony of honeybees, induced to raise a new queen by the beekeeper
Computer systems[edit]
- Nucleus (operating system), sometimes a synonym for kernel
- Nucleus CMS, a weblog system
- Nucleus RTOS, a real-time operating system (RTOS)
- Nucleus, part of an operating system loaded by an Initial Program Load or boot loader
Mathematics[edit]
- Nucleus (algebra), the elements of a ring that associate with all others
- Nucleus (order theory), a mathematical term
Other sciences[edit]
- Nucleus (syllable), in linguistics, the central part of a syllable
- Atomic nucleus, the very dense central region of an atom
- Condensation nucleus, the seed of a raindrop
- Ice nucleus, the seed of a snowflake
Arts and media[edit]
- Nucleus (band), a jazz-rock band from Britain
- Nucleus (video game), a 2007 downloadable game on the PlayStation Store
- Nucleus (Anekdoten album), 1995
- Nucleus (Sonny Rollins album), 1975
- Nucleus, predecessor to Canadian rock band A Foot in Coldwater
- Nucleus, a scientific journal concerned with the cell nucleus; published by Taylor & Francis
Other uses[edit]
- Nucleus (advocacy group), a UK-European political advocacy campaign organisation
- Nucleus Limited, an Australian medical research company, taken over by Pacific Dunlop in 1988
- NuCLEus, a proposed 54-story mixed use building in Cleveland, Ohio, US
- Nucleus, the Nuclear and Caithness Archives, a British national archive
See also[edit]
- Nuclear (disambiguation)
- Nucleation
- Nucleic acid
- Nucleolus
- Core (disambiguation)
1
a
: the small bright body in the head of a comet
b
: the small brighter and denser portion of a galaxy (see galaxy sense 1b)
2
: a central point, group, or mass about which gathering, concentration, or accretion takes place: such as
c
: a characteristic and stable complex of atoms or groups in a molecule (see molecule sense 1)
d
: the positively charged central portion of an atom that comprises nearly all of the atomic mass and that consists of protons and usually neutrons
3
: the peak of sonority in the utterance of a syllable
4
: a basic or essential part : core
players who are the nucleus of the team
Synonyms
Example Sentences
a college campus that was a nucleus of opposition to the war
the nucleus of the movement’s methodology has always been passive resistance
Recent Examples on the Web
In 2008, the Dawgs brought in a talented freshman class featuring Gordan Hayward, Shelvin Mack and Ronald Nored, joining the nucleus of Matt Howard, Zach Hahn and Willie Veasley.
—
Akeem Glaspie, The Indianapolis Star, 29 Mar. 2023
Quarks make up the atomic nucleus.
—Jennifer Ouellette, Ars Technica, 24 Mar. 2023
Strong nucleus returns for Methuen softball Several key players return from last year’s first softball practice at Methuen.
—Nate Weitzer, BostonGlobe.com, 20 Mar. 2023
No nucleus, no master.
—Hannah Grossman, Fox News, 19 Mar. 2023
In collaboration with the Parisian architect Charles Zana, who also designed the low dark green mohair sofa in a back seating area beneath a tall mirrored bar, Nury went about building a home where the kitchen isn’t just the nucleus but the entire atom.
—Kurt Soller David Chow, New York Times, 13 Mar. 2023
Lastly, even the nuclei inside of atoms can touch.
—Paul M. Sutter, Discover Magazine, 7 Mar. 2023
The nucleus from these donor cells is introduced into an egg and activated by chemicals.
—Nadia Leigh-hewitson, CNN, 1 Mar. 2023
Fusion involves pushing together two nuclei of a lightweight element, such as hydrogen, at a colossal speed, forcing them to fuse.
—Harold Maass, The Week, 24 Feb. 2023
See More
These examples are programmatically compiled from various online sources to illustrate current usage of the word ‘nucleus.’ Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.
Word History
Etymology
New Latin, from Latin, kernel, from nuc-, nux nut — more at nut
First Known Use
1668, in the meaning defined at sense 1a
Time Traveler
The first known use of nucleus was
in 1668
Dictionary Entries Near nucleus
Cite this Entry
“Nucleus.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/nucleus. Accessed 14 Apr. 2023.
Share
More from Merriam-Webster on nucleus
Last Updated:
6 Apr 2023
— Updated example sentences
Subscribe to America’s largest dictionary and get thousands more definitions and advanced search—ad free!
Merriam-Webster unabridged
nu·cle·us
(no͞o′klē-əs, nyo͞o′-)
n. pl. nu·cle·i (-klē-ī′) or nu·cle·us·es
1. A central or essential part around which other parts are gathered or grouped; a core: the nucleus of a city.
2. Something regarded as a basis for future development and growth; a kernel: a few paintings that formed the nucleus of a great art collection.
3. Biology A membrane-bound organelle within a eukaryotic cell that contains most of the cell’s genetic material. DNA transcription takes place in the nucleus.
4. Anatomy A group of specialized nerve cells or a localized mass of gray matter in the brain or spinal cord.
5. Physics The positively charged central region of an atom, composed of protons and neutrons, about which negatively charged electrons orbit. Extremely small and dense, the nucleus contains almost all of the mass of an atom.
6. Chemistry A group of atoms bound in a structure, such as a benzene ring, that is resistant to alteration in chemical reactions.
7. Astronomy
a. The central, often brightest part of the head of a comet.
b. The solid part of a comet, composed of ice and smaller amounts of dust and rock.
c. The central, often brightest part of a galaxy.
8. Meteorology A particle on which water vapor molecules accumulate in free air to form a droplet or ice crystal.
9. Linguistics The part of a syllable having the greatest sonority. In the word middlemost (mĭd′l-mōst′) the nuclei of the three syllables are (ĭ), (l), and (ō); in the Czech word krk («neck»), the nucleus is (r).
[Latin nuculeus, nucleus, kernel, from nucula, little nut, diminutive of nux, nuc-, nut.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
nucleus
(ˈnjuːklɪəs)
n, pl -clei (-klɪˌaɪ) or -cleuses
1. a central or fundamental part or thing around which others are grouped; core
2. a centre of growth or development; basis; kernel: the nucleus of an idea.
3. (Biology) biology (in the cells of eukaryotes) a large compartment, bounded by a double membrane, that contains the chromosomes and associated molecules and controls the characteristics and growth of the cell
4. (Anatomy) anatomy any of various groups of nerve cells in the central nervous system
5. (Astronomy) astronomy the central portion in the head of a comet, consisting of small solid particles of ice and frozen gases, which vaporize on approaching the sun to form the coma and tail
6. (General Physics) physics the positively charged dense region at the centre of an atom, composed of protons and neutrons, about which electrons orbit
7. (Chemistry) chem a fundamental group of atoms in a molecule serving as the base structure for related compounds and remaining unchanged during most chemical reactions: the benzene nucleus.
8. (Botany) botany
a. the central point of a starch granule
9. (Phonetics & Phonology) phonetics the most sonorous part of a syllable, usually consisting of a vowel or frictionless continuant
10. (Logic) logic the largest individual that is a mereological part of every member of a given class
[C18: from Latin: kernel, from nux nut]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
nu•cle•us
(ˈnu kli əs, ˈnyu-)
n., pl. -cle•i (-kliˌaɪ)
-cle•us•es.
1. a central part about which other parts are grouped or gathered; core.
2. a specialized, usu. spherical mass of protoplasm encased in a double membrane and found in eukaryotic cells, directing their growth, metabolism, and reproduction, and containing most of the genetic material.
3. the positively charged mass within an atom, composed of neutrons and protons and possessing most of the mass but occupying only a small fraction of the volume of the atom.
4. a mass of nerve cells in the brain or spinal cord in which nerve fibers form connections.
5. a fundamental arrangement of atoms, as the benzene ring, that may occur in many compounds by substitution of atoms without a change in structure.
6. the condensed portion of the head of a comet.
7.
a. the central, most prominent segment in a syllable, consisting of a vowel or vowellike consonant, as the a-sound in cat or the l-sound in bottle.
b. the most prominent syllable in an utterance or stress group; tonic syllable.
[1695–1705; < Latin nuc(u)leus kernel =nuc- (s. of nux) nut + -uleus diminutive suffix]
Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
nu·cle·us
(no͞o′klē-əs)
Plural nuclei (no͞o′klē-ī′)
1. Chemistry The positively charged central region of an atom, composed of protons and neutrons and containing most of the mass of the atom. See more at atom.
2. Biology The structure in the cytoplasm of a living cell that contains the cell’s DNA and controls its metabolism, growth, and reproduction. A nucleus surrounded by a membrane is found in almost all the cells of eukaryotes and thus sets them apart from the cells of prokaryotes, such as bacteria, which do not contain nuclei. See more at cell.
3. Astronomy The solid central part of a comet, composed of ice, frozen gases, and dust.
The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Nucleus
a central mass or number; a collection of persons or items to which addition will be made.
Examples: nucleus of epic cycles, 1835; of a library, 1875; of pain and pleasure, 1876; of physicists—Lipton, 1970; of fine thoughts, 1820.
Dictionary of Collective Nouns and Group Terms. Copyright 2008 The Gale Group, Inc. All rights reserved.
nucleus
1. A cell organelle that contains the chromosomes and directs cell activities.
2. The small (about 10-14 m diameter) core of an atom. All nuclei contain positively charged protons, and all but hydrogen contain neutrons which have zero charge.
3. An atom’s positively charged core containing one or more protons and (except in hydrogen) one or more neutrons.
4. The control center in most types of cell, which contains coded genetic instructions. See chromosome, genes.
Dictionary of Unfamiliar Words by Diagram Group Copyright © 2008 by Diagram Visual Information Limited
Introduction
The word Nucleus is a common term in biology. The Nucleus is an integral component of every cell. The Nucleus is a special type of membrane-bounded structure found in cells. The Nucleus contains a genetic material made up of eukaryotic organisms. In a eukaryotic cell, the Nucleus is present at the center and is the most prominent organelle in the cell, accounting for 10% of cell volume.
For a better understanding of the cell, have a look at its picture
source: toppr.com
A nucleus is defined as a double-membered eukaryotic cell organelle that consists of genetic material (that contains information related to its growth and reproduction) and it is sometimes referred to as a “central unit”. The Nucleus maintains the integrity of the cell through transcription facilities. The Nucleus is the largest organelle in the cell, and it is one of the organelles that can be identified easily under the microscope.
The cell is a functional component and fundamental organization in living things. The cell is the simplest form of construct that contains and defines all the properties assigned to live.
Structure and Parts of Nucleus
The Nucleus is at the center of the cell. The Nucleus contains the genetic material present in the cell. The Nucleus contains the different structural elements that facilitate the functioning of the cell. Here are all the elements in the Nucleus:
Source: justscroll.com
Nucleus DNA
- The nucleus DNA includes significant proportions of the genome in a cell (it’s a tiny part that comes from the extranuclear DNA commonly found in the chloroplasts and mitochondria).
- The DNA that is present outside the Nucleus is called extra-nucleus DNA. Extra Nucleus DNA is similar to cpDNA and is mostly found in mitochondria. At the same time, the other element, i.e., chloroplasts, is presented in multiple places with multiple copies of elements as there are multiple mitochondria and multiple chloroplasts. Still, there is only one Nucleus in a cell.
- The nucleus DNA is grouped into a structure shaped like chromatic through histones, except cpDNA and mtDNA.
- It has thousands of copies in cpDNA and mtDNA.
Chromatin/ chromosomes
- The nucleic acid (RNA and DNA) and proteins (histones) refer to chromatin.
- In cell division, the chromatin is grouped to create a chromosome.
- The main role of the chromosomes or chromatin is to pack the DNA into a smaller size so that it fits into the cell.
- The nucleosome is the basic structural unit of chromatin.
- Heterochromatin and euchromatin are the two main forms of chromatin.
- The euchromatin comes in a loose structure. It allows replication and transcription. On the other side, heterochromatin is less active, condensed, and consequential.
- Each of the nucleosomes includes a segment of DNA wrapped around the protein cores of histone.
Nuclear Bodies
- A nucleus inside the Nucleus is defined as a non-membrane proteinaceous substance in the body. The nucleolus is one of the Nucleus’s popular and important nuclear body parts.
- Other names for nuclear bodies are nuclear dots or nuclear domains. They are structures of membranelles found in the Nucleus in eukaryotic cells.
- The nuclear bodies include the nucleolus promyelocytic leukemia protein.
Nuclear Membrane
- Its primary function is to separate the Nucleus elements. The membrane’s outer layer contains endoplasmic reticulum.
- The endoplasmic reticulum and nuclear envelope are connected so that the inner part of the nuclear envelope continues the connection with the Endoplasmic reticulum’s lumen.
- In between the two layers of the nuclear layer, there is a liquid-filled or perinuclear space.
- The Nucleus enters the cytoplasm through nuclear pores.
- The nuclear membrane consists of lipids and proteins.
Nucleolus
- These are denser, smaller, and round in shape. These are found in Nucleus.
- The Nucleus contains one nucleolus.
- The nucleolus is usually placed at a particular area of the particle chromosome. While the region of this particular chromosome is where it remains attached is known as the secondary constriction.
Nucleoplasm
- The Nucleoplasm is a kind of protoplasm. Moreover, it consists of enzymes, dissolved salts, and organic molecules.
- The nucleoplasm also acts as a cushion in order to protect the chromosomes and nucleolus.
- Additionally, it also helps in maintaining its shape.
Functions of Nucleus
The Nucleus of the cell controls the organism’s characteristics and properties. This organelle also ensures the growth of protein, growth, division of cell protein, and differentiation in the cell. The Nucleus carries all the essential functions in the cell. Here are the following of them listed.
- The Nucleus is known for its storage functions as it stores RNA and proteins in Nucleus.
- Chromatin acts as a storage option for storing the genes in thin and long DNA strands and other materials.
- The Nucleus also functions as an exchanger of the hereditary molecules DNA and RNA between the cell nucleus cell and the rest of the cell particles.
- The cell functions nucleus also performs the production of the ribosomes in the nucleolus.
- The Nucleus also functions as a transcription site where messenger RNA is developed to synthesize the protein.
- During cell division, the chromatins are lined into the Nucleus chromosomes.
- The Nucleus also helps function in the growth and development of the ribosomes in the Nucleus.
- In addition, the nucleus serves as the selective transport for the energy molecules and regulatory factors through the nuclear pores.
- It controls all the biological activities that happen in the cells.
Nucleus Types
There are different types of Nuclei differentiated based on their cell’s presence and absence. Here are those mentioned:
Unicleate cell
This cell is also known as a monokaryotic cell. It is found in plant cells and contains only one nucleus.
Enucleate cell
Those cells which don’t contain the Nucleus are called enucleate cells. Some living creatures like mature sieve tubes and mature mammals lack nuclei.
Bi-nucleate cell
This type of cell is also known as the dikaryotic cell. This cell contains two nuclei. A common example includes paramecium (having micronucleus and mega), liver cells, Balantidium, and bone marrow cells.
Multinucleate cell
This cell is also known as the polynucleated cell, containing more than two nuclei. Common examples containing these types of cells are latex vessels and plants latex cells.
This is all about the Nucleus, its functions of the Nucleus, structure the Nucleus, types of Nuclei, and its distribution.
It is fascinating to observe how life evolved from its earliest predecessor to the organisms which would be multicellular that surround us. According to the cell theory, a cell is the basic building block of life, and that all living things are made up of cells. The method also asserts that pre-existing cells give rise to new ones.
Two scientists, Schleiden and Schwann, proposed the hypothesis that all animals and plants are made up of cells and that a cell is the fundamental building block of life. Virchow extended the cell idea by arguing that all cells are descended from earlier cells. Cells vary in shape and size depending on the type of activity they carry out. Every cell contains a specific component of the cell organelle to carry out a distinct aspect, such as mitochondria for respiration. This indicates that there is a division inside cells.
Nucleus
The nucleus is the part of the cell that is most essential (plural: nuclei). It comes from a Latin term that translates to “nut kernel.”
A double-membraned organelle found in eukaryotic cells known as a nucleus houses the genetic material.
As was previously said, the nucleus is the unique characteristic of eukaryotic cells and is only present in eukaryotes. However, although coming from eukaryotic species, some cells, like RBC’s, lack a nucleus.
Structure
- It is typically the cell organelle that is most easily seen.
- Membranes surround and fully enclose the nucleus.
- The nuclear envelope is the structure that surrounds it.
- The cytoplasm and the nucleus’s contents are separated by the membrane.
- The chromosomes of the cell are also included within it.
- The chromosomes, which contain DNA, supply the genetic data necessary for the synthesis of various cell components as well as for the generation of life.
- The presence of nuclear pores on the envelope of the nucleus facilitates the movement of substances between the nucleus and the cytoplasm.
Function
- It regulates the cell’s growth and reproduction and holds genetic information.
- Proteins would move across the nucleus with help of a signal called a nuclear export signal.
- The genetic makeup of a cell is contained in the nucleus, which has been explained in detail as a membrane-bound structure.
- In addition to serving as a DNA storage space, it also serves as the location of various significant cellular functions.
- In the nucleus, one’s DNA can be duplicated first and foremost. DNA replication is the process that creates an exact duplicate of the DNA.
- Cell division begins with the creation of two exact replicas of the parent or host, with each new cell receiving a unique set of instructions.
- Second, transcription takes place in the nucleus. Different RNA types are produced by transcription from DNA.
- Making copies of various pages of the instructions for the human body that may be moved outside the cell and processed by the remainder of the body is analogous to transcription.
- DNA gets transcribed into RNA, and then into proteins, according to the fundamental biological principle.
Nucleolus
The unique structure found inside the nucleus of eukaryotic cells is called the nucleolus. It mostly takes involvement in ribosome assembly, changing transferring RNA, and detecting oxidative stress. RNA and proteins, which develop around particular chromosomal areas, make up the nucleolus. It is a significant part of the nucleus. The structural elements are made up of the sequence of DNA or RNA, as well as other elements. RNA, DNA, and proteins make up most of the nucleolus.
Structure
The nucleolus in eukaryotic cells has a well-organized structure with 4 main histologic parts. The parts can also be categorized as follows:
- The ribosome proteins are produced inside the fibrillar centers.
- Granular Components: Such parts contain RNA which interacts with ribosomal proteins, leading to the creation of ribosomes.
- The ribosomal proteins are connected to the newly produced RNA via thick microfibrils constituents.
- All plants include nucleolus vacuoles.
- An electron microscope makes it simple to see the nucleolus’ structure and function. Fluorescence restoration following photoinhibition and fluorescent labeling are two approaches that provide for a clear understanding of the nucleolus’ structure inside the cell.
- Contrary to animal and human nuclei, certain species of plants have very increased iron levels in their nuclei.
Function
rRNAsynthesis and ribosomal biosynthesis are the primary functions of the nucleolus, and this is the most noticeable region in the nucleus of eukaryotic cells. The nucleolus is also thought to play a role in the cell cycle regulation, growth, aging, activity of telomerase, and also the silencing of genes and reactions to abiotic or biotic stressors, according to mounting data. During the first section of the analysis, they quickly evaluate the plant’s composition and characteristics’ traditional activities in rRNA production and ribosome assembly as well as potential participation in additional RNA regulatory processes such as spliced, nonsense-mediated mRNA destruction, and RNA silencing. In the second section of the review, we evaluate recent developments and talk about the nucleolus’s well-known and potential future responsibilities.
The nucleolus, which occupies over 25percent of the total nucleus’ volume, is referred to as the brain of the nucleus. It primarily participates in the synthesis of the constituent parts of ribosomes. Thus, in eukaryotic cells, the nucleolus is crucial for the creation of ribosomes and the production of proteins.
Frequently Asked Questions
Question 1: Describe the nucleus?
Answer:
The genetic information and other instructions necessary for cellular functions are found in the double membrane organelle known as the nucleus. It is one of the biggest organelles and is only present in eukaryotic cells.
Question 2: Describe the nucleus’s structure?
Answer:
- The nuclear membrane/envelope, a double membrane organelle, surrounds the nucleus.
- Within the nucleus, the nucleolus can be observed, taking roughly 25% of the space.
- The nucleus contains thick, thread-like structures called chromatin that hold proteins and DNA.
- The nuclear matrix, a web of strands and tangles that serves comparable purposes to the cytoskeleton, gives the nucleus its mechanical strength.
Question 3: Describe various operations of the nucleus?
Answer:
- The nucleus serves two main purposes:
- It is in charge of keeping the DNA or other genetic material within the cell.
- It is in charge of organizing a variety of crucial cellular processes, including the synthesis of proteins, cell division, growth, and a number of other crucial operations.
Question 4: Which organism would have the two nuclei?
Answer:
Single-celled cilia protozoa called Paramecium contain 2 nuclei, in which one would be micro and the other would-be macro. The macronucleus of a cell stores the genes necessary for basic cellular functions, while the micronucleus regulates sexual reproduction.
Question 5: Describe nuclear pores?
Answer:
The presence of nuclear pores on the nuclear envelope facilitates the movement of substances between the cytoplasm and nucleus.
Question 6: What is the importance of the nuclear export signal?
Answer:
This would play an essential role in and out of the proteins across the nucleus through the pores of the nucleus. These would be the sequence of amino acids.