write detail note on nucleus
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The nucleus is a membrane bound structure that contains the cell's hereditary information and controls the cell's growth and reproduction. It is commonly the most prominent organelle in the cell.
The nucleus is surrounded by a structure called the nuclear envelope. This membrane separates the contents of the nucleus from the cytoplasm. The cell's chromosomes are also housed within the nucleus. Chromosomes contain DNA which provides the genetic information necessary for the production of other cell components and for the reproduction of life
In cell biology, the nucleus (pl. nuclei; from Latin nucleus or nuculeus, meaning kernel or seed) is a membrane-bound 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 including osteoclasts have many.
The cell nucleus contains all of the cell's genome, except for a small fraction of mitochondrial DNA, organized as multiple long linear DNA molecules in a complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these chromosomes 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 (which includes the nuclear lamina), a network within the nucleus that adds mechanical support, much like the cytoskeleton, which supports the cell as a whole.
Because the nuclear envelope is impermeable to large molecules, nuclear pores are required to 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 subcompartments, its contents are not uniform, and a number of 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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Structure of Nucleus
✏️Nucleus is a membrane bound structure that contains the cell’s hereditary information and controls the cell’s growth and reproduction.
✏️Nucleus is present in all eukaryotic cells, they may be absent in few cells like the mammalian RBCs.
✏️The shape of the nucleus is mostly round, it may be oval, disc shaped depending on the type of cell.
✏️It is the command center of a eukaryotic cell and is commonly the most prominent organelle in a cell.
✏️The nuclear envelope is a double membrane that separates the nucleus from the cytoplasm.
✏️All traffic into and out of the nucleus passes through nuclear pores that bridge the double membranes.
✏️Inbound traffic includes all nuclear proteins and ribosomal proteins destined for the nucleolus.
✏️Outbound traffic includes mRNAs and ribosomal subunits.
✏️The nuclear envelope consists of phospholipids that form a lipid bilayer.
✏️The nuclear envelope is perforated with numerous pores called nuclear pores.
✏️The envelope helps to maintain the shape of the nucleus and assists in regulating the flow of molecules into and out of the nucleus through nuclear pores.
✏️The nuclear envelope is connected with the endoplasmic reticulum (ER) in such a way that the internal compartment of the nuclear envelope is continuous with the lumen of the ER.
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