Nucleus
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The nucleus is a large membrane-bound organelle found at the center of eukaryotic cells that contains the cell's genetic material in the form of chromosomes. It directs the cell's activities and is involved in cellular reproduction. Key features include being visible under a light microscope due to its acidic nature, containing DNA, RNA, and the nucleolus which produces ribosomes. The nuclear envelope encloses the nucleus and contains pores that regulate material passing in and out.
Nucleus
- 2. • In the centre of all eukaryotic cells, there is a large prominent membrane- bound organelle known as the nucleus. Some features of nucleus are as follows: • The nucleus is visible under a light microscope. It is acidic in nature. Any basic stain can be used to see the nucleus. • It is also present in prokaryotes, but it lacks a well-defined membrane. • Generally, one nucleus is present in a cell; however, there are certain eukaryotic cells which do not contain even a single nucleus (e.g., red blood cell) and there are certain others that contain more than one nucleus i.e. they are multinucleate (e.g., slime mould). • In some organisms like bacteria, the nuclear region of the cell may be poorly defined due to the absence of a
- 3. • The nucleus was the first organelle to be discovered. What is most likely the oldest preserved drawing dates back to the early microscopist Antonie van Leeuwenhoek (1632 – 1723). He observed a "Lumen", the nucleus, in the red blood cells of salmon. Unlike mammalian red blood cells, those of other vertebrates still possess nuclei. The nucleus was also described by Franz Bauer in 1804 and in more detail in 1831 by Scottish botanist Robert Brown in a talk at the Linnean Society of London. Brown was studying orchids under microscope when he observed an opaque area, which he called the areola or nucleus, in the cells of the flower's outer layer. He did not suggest a potential function. In 1838, Matthias Schleiden proposed that the nucleus plays a role in generating cells, thus he introduced the
- 4. The following points list the various parts of the nucleus with their respective functions. •Nuclear envelope: The nucleus is enclosed by a double-layered cellular membrane called the nuclear envelope. The nuclear envelope separates the contents of the nucleus from the cytoplasm. The nuclear membrane is pierced with holes known as the nuclear pores. These pores allow the nucleus to communicate with the rest of the cell as they control the passage of substances into and out of the nucleus. •Nucleolus: When observed under a microscope, the centre of the nucleus has a dark dense spherical area known as the nucleolus. The nucleolus is the production factory of ribosomes, which in turn manufacture proteins.Thus, it can be said that the nucleolus Is Indirectly involved In protein and RNA synthesis. •Nucleoplasm:The nucleus contains nuclear sap or a semi-fluid matrix enclosed by the Nuclear envelope. This is known as the Nucleoplasm. It holds the nucleolus and the suspended chromatin. Chromatin network: The nucleus contains the genetic material of an organism in t the form of a
- 5. • Inside the nucleus, rod-shaped structures called chromosomes are present. These chromosomes bear the hereditary units known as genes. Genes are the segments of DNA which provide information for carrying out the regular metabolic activity of a cell. For example, DNA contains the information on how to make the proteins of the cells. The proteins, in turn, control the chemical reactions of the cells and provide structural support to both the cells and tissues. The nucleus also plays a crucial part, along with the environment, in determining the way a cell will develop and the form that it will exhibit at maturity by directing the chemical activities of the cell. Thus, also known as the director of the cell.
- 6. • The nucleus controls all metabolic activities of a cell. • It is concerned with the transmission of hereditary traits from the parent to the offspring. • It plays an important role in cellular reproduction —the process by which a single cell divides to form two new cells. • It also plays a crucial part in determining the way a cell will develop and the form it will exhibit at maturity. It does this by directing the chemical activities of the cell.
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