Cell nucleus

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Cell nucleus

The largest of the membrane-bounded organelles which characterize eukaryotic cells; it is thought of as the control center since it contains the bulk of the cell's genetic information in the form of deoxyribonucleic acid (DNA). The nucleus has two major functions: (1) It is the site of synthesis of ribonucleic acid (RNA), which in turn directs the formation of the protein molecules on which all life depends; and (2) in any cell preparing for division, the nucleus precisely duplicates its DNA for later distribution to cell progeny. See Deoxyribonucleic acid (DNA), Eukaryotae, Ribonucleic acid (RNA)

The diameter of nuclei ranges from 1 micrometer in intracellular parasites and yeast cells to several millimeters in some insect sperm. Spherical or ellipsoidal nuclei are found in most cell types, although occasionally spindle-shaped, lobulated, disc-shaped, or cup-shaped nuclei may be observed. Although nuclear size and shape are somewhat consistent features of a particular cell type, these features are more variable in cancer cells. In addition, tumor cell nuclei are characterized by indentation, furrowing, elongation, and budding.

The nucleus is bounded by a double membrane (the nuclear envelope) and contains several major components: chromatin, which is composed of DNA and chromosomal proteins; the nucleolus, which is the site of ribosomal RNA (rRNA) synthesis; and nucleoplasmic fibrils and granules, some of which are involved in the processing and transport of messenger RNA out of the nucleus (see illustration). The constituents of the nucleus are contained within a framework referred to as the nuclear matrix.

Transmission electron micrograph of a thin section of a rat liver cell nucleusenlarge picture
Transmission electron micrograph of a thin section of a rat liver cell nucleus
References in periodicals archive ?
HMGB1 is a ubiquitous nuclear protein that can be released by any damaged cell or by activated macrophages and certain other cell types.
Cells regulate nuclear protein transport at multiple levels through a number of mechanisms.
By changing the antibodies of the nuclear protein and the combination of molecules that bind to the gene, the kit can also be used to detect the H7N9 and H5N1 strains of viruses, which are resistant to anti-flu medicine Tamiflu, and the dengue fever virus.
Using antibodies which cross-react with a nuclear protein PCYT1A when testing for ERCC1 may potentially lead to an incorrect IHC test result," says Wei-Wu He, Ph.
9) However, aberrant expression of the FOXL2 nuclear protein has been demonstrated in testicular juvenile GCTs by immunofluorescense.
We have genomics and proteomics that tell us about where genes are, whether they are functioning, and interactions of genes with proteins, but no one had focused on the changing distribution of nuclear proteins," Lelievre concludes.
The nonchromatin, nucleoskeletal structures found in mammalian nuclei comprise ribonucleoproteins, the nucleolus, and an in situ nuclear protein matrix associated with internal peripheral structures of the nucleus [111.
Orn of the University of Minnesota in Minneapolis have seen nuclear protein deposits in mice with a condition similar to the human disease spinocerebellar ataxia type 1.
BRD4-NUT is a fusion protein containing the BRD4 bromodomain and the nuclear protein in testis (NUT) protein that results from a chromosomal translocation.
Distinguishing high-grade epithelial malignancies such as sinonasal undifferentiated carcinoma, undifferentiated nonkeratinizing squamous cell carcinomas including nasopharyngeal carcinoma, and nuclear protein in testis (NUT) midline carcinomas (NMCs) of the upper aerodigestive tract can be particularly difficult.
In some experiments, nuclear extracts were incubated with a 50 molar excess of unlabeled probe or an unlabeled probe from a different binding motif to examine the specificity of nuclear protein binding to the oligonucleotides.

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