What is within a nucleus of a cell?
6235#1
Cell nuclei contain most of the cell's genetic material, 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 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 (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.
Cell nucleus
6235#7
The nucleus is the largest cellular organelle in animal cells.
In mammalian cells, the average diameter of the nucleus is approximately 6 micrometres (µm), which occupies about 10% of the total cell volume. The viscous liquid within it is called nucleoplasm (or karyolymph), and is similar in composition to the cytosol found outside the nucleus. It appears as a dense, roughly spherical or irregular organelle. The composition by dry weight of the nucleus is approximately: DNA 9%, RNA 1%, Histone Protein 11%, Residual Protein 14%, Acidic Proteins 65%.
Cell nucleus
5184#0
In cell biology, the cytoplasm is all of the material within a cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The main components of the cytoplasm are cytosol – a gel-like substance, the organelles – the cell's internal sub-structures, and various cytoplasmic inclusions. The cytoplasm is about 80% water and usually colorless.
Cytoplasm
47719891#9
In cells, DNA is housed in the nucleus and it never leaves. The DNA within the nucleus is transcribed by tRNA, and the transcriptions of the DNA become RNA. The RNA (ribonucleic acid) leaves the nucleus to float freely around the cytoplasm, and it contains the instructions of the DNA that are vital to the coding, decoding, regulation and expression of genes. The ribosomes then take the RNA messages and turn them into proteins that build cells. When a virus enters a cell and inserts its DNA code into the nucleus, it gets transcribed and released into the cell for the ribosome to make it into a protein. This is how viral infections occur. The cell then explodes with the overproduction of the virus, releasing it into the body to infect any and all other cells it finds. It is theorized that through evolution, cells developed a defense system called RNAi (RNA interference) to stop the production of the proteins that have suspicious mirror image messages of the RNA. They don’t just destroy the suspicious messages, but the correct messages as well to stop all production of that message. This is a cell’s self-destruct mechanism and every cell, plant and animal, have RNAi: a way to turn off the production of a certain gene inside the protein.
Cell communication (biology)
23389705#2
"Marteilia" has a very peculiar morphology. The outermost cell is the primary cell. Within the primary cell, there is a nucleus and between 3 and 16 secondary cells. Within a secondary cell, there is a nucleus and between 1 to 6 spores. Within each spore, there is a nucleus and another spore, which has yet another nucleus and spore within. This spore within a spore within a spore is termed a tricellular spore. "Marteilia" has tricellular spores where as the similar genera "Paramarteilia" and "Paramyxa" have bicellular and tetracellular spores respectively (Feist, Hine, Bateman, Stentiford, & Longshaw, 2009).
Marteilia
54176#7
Cells in the body function because of DNA. DNA sits within the nucleus of a cell. Here, parts of DNA are copied and sent to the body of the cell via RNA. The RNA is then used to create proteins which form the basis for cells, their activity, and their products. Proteins dictate cell function and gene expression, a cell is able to self-regulate by the amount of proteins produced. However, not all cells have DNA – some cells such as mature red blood cells lose their nucleus as they mature.
Human body
337071#0
In neuroanatomy, a nucleus (plural form: nuclei) is a cluster of neurons in the central nervous system, located deep within the cerebral hemispheres and brainstem. The neurons in one nucleus usually have roughly similar connections and functions. Nuclei are connected to other nuclei by tracts, the bundles (fascicles) of axons (nerve fibers) extending from the cell bodies. A nucleus is one of the two most common forms of nerve cell organization, the other being layered structures such as the cerebral cortex or cerebellar cortex. In anatomical sections, a nucleus shows up as a region of gray matter, often bordered by white matter. The vertebrate brain contains hundreds of distinguishable nuclei, varying widely in shape and size. A nucleus may itself have a complex internal structure, with multiple types of neurons arranged in clumps (subnuclei) or layers.
Nucleus (neuroanatomy)
10704375#1
Unlike many nuclei within the central nervous system (CNS), the mesencephalic nucleus contains no chemical synapses but are electrically coupled. Neurons of this nucleus are unipolar cells that receive proprioceptive information from the mandible and send projections to the trigeminal motor nucleus to mediate monosynaptic jaw jerk reflexes. It is also the only structure in the CNS to contain first order sensory neurons, cell bodies of primary afferents in contact with the periphery, which are usually contained within ganglia (like the trigeminal ganglion). The mesencephalic nucleus can thus be considered functionally as a sensory ganglion embedded within the brainstem, making it neuroanatomically unique .
Mesencephalic nucleus of trigeminal nerve
6241559#5
The nucleus of the cell lies between the anterior lobes of the chloroplast in parallel with the pyrenoid, and some species have developed anterior nuclear lobes. The nucleus is centrally located and is parallel with the flagellar depression and pyrenoid. Additionally, condensed chromatin can be viewed in the nucleus of certain species. See figure 1 for nuclear positioning within cells. The Golgi of "Tetraselmis" species has a distinct number of Golgi bodies usually within the range of 2-4, but species can have up to 8 or more. This is a reliable characteristic that is used to help classify species. Golgi bodies lie between the chloroplast and the basal bodies; cis-Golgi face the chloroplast and trans-Golgi face the basal bodies. Mitochondria are dispersed throughout the cytoplasm in no pattern. The cytoplasm may contain additional organelles and macromolecules such as lipid droplets, vacuoles, and lysosomes. Additionally, the starch produced by "Tetraselmis" is the same as those produced from land plants.
Tetraselmis
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The first model known as the "syntrophic model" proposes that a symbiotic relationship between the archaea and bacteria created the nucleus-containing eukaryotic cell. (Organisms of the Archaea and Bacteria domain have no cell nucleus.) It is hypothesized that the symbiosis originated when ancient archaea, similar to modern methanogenic archaea, invaded and lived within bacteria similar to modern myxobacteria, eventually forming the early nucleus. This theory is analogous to the accepted theory for the origin of eukaryotic mitochondria and chloroplasts, which are thought to have developed from a similar endosymbiotic relationship between proto-eukaryotes and aerobic bacteria. The archaeal origin of the nucleus is supported by observations that archaea and eukarya have similar genes for certain proteins, including histones. Observations that myxobacteria are motile, can form multicellular complexes, and possess kinases and G proteins similar to eukarya, support a bacterial origin for the eukaryotic cell.
Cell nucleus