News tagged with cell nuclei
In cell biology, the nucleus (pl. nuclei; from Latin nucleus or nuculeus, or kernel), also sometimes referred to as the "control center", is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these chromosomes are the cell's nuclear genome. The function of the nucleus is to maintain the integrity of these genes and to control the activities of the cell by regulating gene expression--the nucleus is therefore the control center of the cell.
The main structures making up the nucleus are the nuclear envelope, a double membrane that encloses the entire organelle and separates its contents from the cellular cytoplasm, and the nuclear lamina, a meshwork within the nucleus that adds mechanical support, much like the cytoskeleton supports the cell as a whole. Because the nuclear membrane is impermeable to most molecules, nuclear pores are required to allow movement of molecules across the envelope. These pores cross both of the membranes, providing a channel that allows free movement of small molecules and ions. The movement of larger molecules such as proteins is carefully controlled, and requires active transport regulated by carrier proteins. Nuclear transport is crucial to cell function, as movement through the pores is required for both gene expression and chromosomal maintenance.
Although the interior of the nucleus does not contain any membrane-bound subcompartments, its contents are not uniform, and a number of subnuclear bodies exist, made up of unique proteins, RNA molecules, and particular parts of the chromosomes. The best known of these is the nucleolus, which is mainly involved in the assembly of ribosomes. After being produced in the nucleolus, ribosomes are exported to the cytoplasm where they translate mRNA.
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Misshapen cell nuclei are frequently observed in the cells of people with cancer and other diseases, but what causes the abnormality—and why it is associated with certain disorders—has remained unclear.
Cancer Feb 19, 2013 | 4.8 / 5 (4) | 0 |
(Medical Xpress) -- Johns Hopkins researchers say they have discovered one of the most important cellular mechanisms driving the growth and progression of meningioma, the most common form of brain and spinal cord tumor. A ...
Cancer Jun 13, 2012 | 5 / 5 (1) | 0
(Medical Xpress) -- If you throw a rubber balloon filled with water against a wall, it will spread out and deform on impact, while the same balloon filled with honey, which is more viscous, will deform much ...
Medical research May 01, 2012 | 5 / 5 (1) | 0 |
Whitehead Institute scientists report that patients whose estrogen receptor (ER)-positive breast cancers have high levels of the ancient cellular survival factor heat shock factor 1 (HSF1) experience poor ...
Cancer Oct 31, 2011 | not rated yet | 0 |
The embryonic nervous system is a hollow tube consisting of elongated neural progenitor cells, which extend from the inner to the outer surface of the tube. In a section inside the tube called the ventricular ...
Neuroscience Jun 10, 2011 | not rated yet | 0