Psychology & Psychiatry

Highly specific synaptic plasticity in addiction

Addiction, or substance use disorder (SUD), is a complex neurological condition that includes drug-seeking behavior among other cognitive, emotional and behavioral features. Synaptic plasticity, or changes in the way neurons ...

Genetics

New molecular structures associated with ALS

Researchers from the University of Seville and the University of Pavia have identified a link between Amyotrophic Lateral Sclerosis (ALS) and the accumulation of DNA-RNA hybrids in the genome. The accumulation of these hybrids ...

Neuroscience

Cytoplasmic traffic jam disrupts sleep-wake cycles

KAIST mathematicians and their collaborators at Florida State University have identified the principle of how aging and diseases like dementia and obesity cause sleep disorders. A combination of mathematical modeling and ...

Neuroscience

New tool for watching and controlling neural activity

A new molecular probe from Stanford University could help reveal how our brains think and remember. This tool, called Fast Light and Calcium-Regulated Expression or FLiCRE (pronounced "flicker"), can be sent inside any cell ...

Oncology & Cancer

How cancer cells escape crowded tumors

Like people, cells in the human body protect their personal space. They seem to know how much space they need, and if it gets too tight, most cells prefer to break free. The mechanism enabling cells to evade crowded environments ...

Neuroscience

Brain imaging can predict childhood weight gain

A greater density of cells in a key reward center of the brain is associated with obesity in children and predicts future weight gain, a new Yale-led study finds.

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Cell nucleus

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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