What blocks bird flu in human cells?

Normally, bird flu viruses do not spread easily from person to person. But if this does happen, it could trigger a pandemic. Researchers from the MDC and RKI have now explained in the journal Nature Communications what makes ...

How our single-celled relatives package their DNA

A group of single-celled organisms organises its DNA in a similar way to higher organisms such as plants, animals, and fungi. However, the way packaged DNA is read out differs between the two related groups, Bram Henneman ...

Scientists detail how chromosomes reorganize after cell division

Researchers have discovered key mechanisms and structural details of a fundamental biological process—how a cell nucleus and its chromosomal material reorganizes itself after cell division. The new findings in chromosomal ...

The filaments that structure DNA

They play a leading role not only in muscle cells: Actin filaments are one of the most abundant proteins in all mammalian cells. The filigree structures form an important part of the cytoskeleton and locomotor system. Cell ...

Neural network fills in data gaps for spatial analysis of chromosomes

Computational methods used to fill in missing pixels in low-quality images or video also can help scientists provide missing information for how DNA is organized in the cell, computational biologists at Carnegie Mellon University ...

How cells protect themselves from mitochondrial defects

Cells need powerhouses known as mitochondria to utilize the energy stored in our food. Most of the proteins required for this powerhouse function are encoded in the nucleus and transported into the mitochondria after they ...

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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.

This text uses material from Wikipedia, licensed under CC BY-SA