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 ?
In a paper published on 3rd June in Science, researchers at the Centre for Genomic Regulation (CRG) led by senior group leader Miguel Beato in collaboration with the University Pompeu Fabra, the Institute for Biomedical Research in Barcelona, and the University Rovira i Virgili in Tarragona, Spain, have described for the first time a new pathway generating energy within the cell nucleus for remodelling chromatin and reprogramming gene expression.
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The Harvard confocal light scattering spectroscopic (CLSS) microscope achieves pictures of 100-nm organelles with 5-nm accuracy, allowing it to look for clumping of the genetic material known as chromatin, an early sign of cancer, inside the cell nucleus.
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Moreover, synergy with late-acting strand transfer inhibitors most likely originates from the early anti-IN effect of SQLs which act before viral DNA can reach the cell nucleus, thus reinforcing the interest for this novel antiviral mechanism.
A gene therapy vector is used to deliver a therapeutic gene or a portion of DNA into a cell nucleus similar to how a syringe is used to inject medicines.
He has identified DNA markers not from the cell nucleus, as Molbo does, but from mitochondria, the cell powerhouses.
Most loops of DNA thrown into a cell nucleus will be eliminated within a few days.
Previously it was known to work in the cell nucleus by regulating key cellular processes such as cell cycle control, cell death and DNA repair.
During 6 to 12 days of observation, the plasmids induced the cells to produce the Math 1 protein, which turns on or off other genes in the cell nucleus.
Allis' research explores the intricacies of chromatin, the DNA-protein complex that efficiently packages the genetic information inside each cell nucleus.