Short note about nucleus of a cell.
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In cell biology, the nucleus is a membrane-enclosed organelle found in eukaryotic cells.
Eukaryotes usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei, and a few others have many.
Cell nuclei contain 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 and are structured in such a way to promote cell function.
The nucleus maintains the integrity of genes and controls 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 isolates its contents from the cellular cytoplasm, and the nuclear matrix, a network within the nucleus that adds mechanical support, much like the cytoskeleton, which supports the cell as a whole.
Because the nuclear membrane is impermeable to large molecules, nuclear pores are required that regulate nuclear transport of molecules across the envelope.
The pores cross both nuclear membranes, providing a channel through which larger molecules must be actively transported by carrier proteins while allowing free movement of small molecules and ions.
Movement of large molecules such as proteins and RNA through the pores is required for both gene expression and the maintenance of chromosomes.
Although the interior of the nucleus does not contain any membrane-bound sub compartments, its contents are not uniform, and a number of sub-nuclear 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.
Eukaryotes usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei, and a few others have many.
Cell nuclei contain 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 and are structured in such a way to promote cell function.
The nucleus maintains the integrity of genes and controls 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 isolates its contents from the cellular cytoplasm, and the nuclear matrix, a network within the nucleus that adds mechanical support, much like the cytoskeleton, which supports the cell as a whole.
Because the nuclear membrane is impermeable to large molecules, nuclear pores are required that regulate nuclear transport of molecules across the envelope.
The pores cross both nuclear membranes, providing a channel through which larger molecules must be actively transported by carrier proteins while allowing free movement of small molecules and ions.
Movement of large molecules such as proteins and RNA through the pores is required for both gene expression and the maintenance of chromosomes.
Although the interior of the nucleus does not contain any membrane-bound sub compartments, its contents are not uniform, and a number of sub-nuclear 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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•The nucleus is a dense protoplasmic body whose position in plant cell is towards periphery.
•In animal cell its position towards the centre.
• It is usually oval or spherical in shape.
•lt was discovered by Robert Brown. It's function is to control all the metabolic activities as well as formation of various organelles by controlling the synthesis of proteins therefore it is called control center of the cell.
•Inside the nucleus is present a clear jelly like substance called nucleoplasm. •Inside the nucleoplasm is present
nucleolus and chromatin network.
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