Dictionary » N » Nucleus



noun, plural: nuclei

(general) The core or the central part around which other parts are grouped or gathered.

(biology) The large, membrane-bounded organelle that contains the genetic material, in the form of multiple linear DNA molecules organized into structures called chromosomes.


In biology, the major functions of nucleus are to maintain the integrity of DNA and to control cellular activities such as metabolism, growth, and reproduction by regulating gene expression. It has three main components: the nucleolus, the chromatin and the nuclear envelope. The nuclear envelope has nuclear pores to control the movement of molecules between the nucleoplasm and the cytoplasm.

In other fields, such as:

In Physics, a nucleus refers to the positively-charged center of an atom that usually contains the protons and neutrons.

In Chemistry, a nucleus is a fundamental arrangement of atoms that occur in compounds through substitution of atoms without a change in structure.

In Astronomy, a nucleus is the center of the head of a comet or the central or brightest part of a nebula or galaxy.

In Meteorology, a nucleus is a particle on which water vapor molecules accumulate in free air to form water drops or ice crystals.

In Botany, a nucleus is the central kernel of a nut or seed, or the center of a starch granule.

In Anatomy, a nucleus is a group of specialized nerve cells in the brain or spinal cord.

Word origin: L: kernel, syncopated var. of nuculeus, equiv. to nucu(la) little nut (nuc-, s. of nux nut + -ula -ULE) + -leus n. suffix.

Related forms: nuclear (adjective).

See also: cell, organelle.

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Re: Totipotent Stem Cell From Molecular Components

... a diploid set from the rest of the DNA and use the rest of the DNA for PCR. I form the histone proteins at the same time that I am forming the nucleus and put the histone proteins in the test tube with the diploid set of chromosomes, make sure there is no more than 1 chromosome per histone, ...

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by caters
Fri Aug 01, 2014 1:42 am
Forum: Cell Biology
Topic: Totipotent Stem Cell From Molecular Components
Replies: 2
Views: 3331

Spontaneous formation of nuclear membrane

I have doubt regarding double membranes around nucleus. Single membrane structures may be formed spontaneously due to amphipathic nature phospholipids. But how double membrane architecture in nucleus form spontaneously after each cell division? ...

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by josem
Sun Jun 22, 2014 1:14 am
Forum: Cell Biology
Topic: Spontaneous formation of nuclear membrane
Replies: 1
Views: 994

Please help me identify this cell

I'm no histologist and especially not experienced with animal tissues, but I'd guess it would be the nucleus and the cell. Where else would you have the cell? Do not forget there can be also white blood cells.

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by JackBean
Sun May 04, 2014 12:09 pm
Forum: Cell Biology
Topic: Please help me identify this cell
Replies: 2
Views: 1500

Please help me identify this cell

... tell me what kind of cell this was in the center. The light purple oval with the small purple dot is the one that interests me. Is the dot the nucleus and the light purple oval is the rest of the cell, or is it the nucleolus and the light purple is the nucleus? I want to guess from the histology ...

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by Marauder21
Thu Apr 10, 2014 5:01 am
Forum: Cell Biology
Topic: Please help me identify this cell
Replies: 2
Views: 1500

Newbie question about the first life

... and eukaryotic cells is relatively recent and was made possible when the electronic microscope was developed and it was seen that bacteria have no nucleus and that all other kinds of cells do have one. This changed the way in which creatures are classified. The big difference was not really between ...

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by piscilactovegetarian
Fri Feb 28, 2014 12:10 am
Forum: Molecular Biology
Topic: Newbie question about the first life
Replies: 14
Views: 10511
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