Khác biệt giữa bản sửa đổi của “Thành viên:Nguyentrongphu/nháp”
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[[File:HeLa cells stained with Hoechst 33258.jpg|thumb|upright=1.6|right|[[HeLa|tế bào HeLa]] được nhuộm bằng kỹ thuật [[nhuộm Hoechst]] để [[DNA]] trong nhân phát ra màu [[huỳnh quang]] xanh nước biển. Tế bào ở giữa và bên phải đang trong [[kỳ trung gian]] nên có thể thấy được toàn bộ nhân của chúng. Còn tế bào bên trái thì đang trong quá trình nguyên phân và DNA của nó đã cô đặc lại.]]
{{Organelle diagram}}
In [[cell biology]], the '''nucleus''' (pl. '''''nuclei'''''; from [[Latin]] {{lang|la|nucleus}} or {{lang|la|nuculeus}}, meaning ''kernel'' or ''seed'') is a [[biological membrane#Function|membrane-bound]] [[organelle]] found in [[eukaryote|eukaryotic]] [[cell (biology)|cells]]. Eukaryotes usually have a single nucleus, but a few cell types, such as mammalian [[red blood cell]]s, have [[#Anucleated_cells|no nuclei]], and a few others including [[osteoclast]]s have [[Multinucleate|many]]. 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]] supports the cell as a whole.
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 [[protein complex|complex]] with a large variety of [[protein]]s, such as [[histone]]s, to form [[chromosome]]s. The [[gene]]s within these chromosomes are [[Nuclear organization|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.
Because the nuclear envelope is impermeable to large molecules, [[nuclear pore]]s are required to regulate [[nuclear transport]] of molecules across the envelope. The pores cross both nuclear membranes, providing a [[Ion channel|channel]] through which larger molecules must be actively transported by carrier proteins while allowing free movement of small molecules and [[ion]]s. 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 [[ribosome]]s. After being produced in the nucleolus, ribosomes are exported to the cytoplasm where they translate [[mRNA]].
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