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Topic: Cell nucleus

	Biology4Kids.com: Cell Structure: Cell Nucleus
		The nucleus is not always in the center of the cell.
		The nuclear envelope is a membrane similar to the cell membrane around the whole cell.
		When the cell is in a resting state there is something called chromatin in the nucleus.
	www.biology4kids.com /files/cell_nucleus.html (359 words)

	Cell Models: An Interactive Animation
		The DNA is similar in every cell of the body, but depending on the specific cell type, some genes may be turned on or off - that's why a liver cell is different from a muscle cell, and a muscle cell is different from a fat cell.
		Nucleolus: The prominent structure in the nucleus is the nucleolus.
		Messenger RNA from the cell nucleus is moved systematically along the ribosome where transfer RNA adds individual amino acid molecules to the lengthening protein chain.
	www.cellsalive.com /cells/cell_model.htm (1286 words)

	The Cell Cycle & Mitosis Tutorial
		The cell is engaged in metabolic activity and performing its prepare for mitosis (the next four phases that lead up to and include nuclear division).
		In animal cells, cytokinesis results when a fiber ring composed of a protein called actin around the center of the cell contracts pinching the cell into two daughter cells, each with one nucleus.
		In plant cells, the rigid wall requires that a cell plate be synthesized between the two daughter cells.
	www.biology.arizona.edu /cell_bio/tutorials/cell_cycle/cells3.html (357 words)

	Euchromatin Network Home Page.
		With increasing accuracy, resolution, and sensitivity, our cell biology methods are revealing new and important information about the role of active euchromatin in the life of the cell, during embryogenesis and cell differentiation, during the hormone response and the immune response, during neoplasia and organ regeneration.
		RNA is now being recognized as the "spark" whereby the cell activates specific genes of the genome for expression in the cell.
		Frenster JH, (1974), in: "Biochemistry of the Cell Nucleus.
	www.euchromatin.net (647 words)

	Research News: Regulating the Nuclear Architecture of the Cell
		BERKELEY, CA — An organelle called the nucleolus resides deep within the cell nucleus and performs one of the cell's most critical functions: it manufactures ribosomes, the molecular machines that convert the genetic information carried by messenger RNA into proteins that do the work of life.
		The organization of structures in the cell's nucleus has profound effects on such essential functions as how and when genes are expressed.
		Controlling functions of the cell and organism through nuclear architecture and spatial rearrangements is known as epigenetics — from the Greek for "on, over, or at" the genes, instead of by the DNA sequence.
	www.lbl.gov /Science-Articles/Archive/LSD-cell-architecture.html (1626 words)

	Cell nucleus - Wikipedia, the free encyclopedia
		In cell biology, the nucleus (from Latin nucleus or nuculeus, kernel) is found in all eukaryotic cells and contains the nuclear genes which form most of the cell's genetic material.
		Regions of DNA which constitute heterochromatin generally contain genes which are not expressed by the cell (this type of heterochromatin is known as facultative heterochromatin) or are regions which make up the telomeres and centromeres of the chromosomes (this type of heterochromatin is known as constitutive heterochromatin).
		A nucleolus is a densely-stained structure in the nucleus where ribosome subunits are assembled.
	en.wikipedia.org /wiki/Cell_nucleus (487 words)

	Cell (biology) - Wikipedia, the free encyclopedia
		The cell is the structural and functional unit of all living organisms, and is sometimes called the "building block of life." Some organisms, such as bacteria, are unicellular, consisting of a single cell.
		The cytoplasm of a eukaryotic cell is surrounded by a plasma membrane.
		This membrane serves to separate and protect a cell from its surrounding environment and is made mostly from a double layer of lipids (hydrophobic fat-like molecules) and hydrophilic phosphorous molecules.
	en.wikipedia.org /wiki/Cell_(biology) (3606 words)

	Animal Cell Nucleus
		Cell Nucleus, The - an examination of structure/function...
		Animal cells are typical of the eukaryotic cell, enclosed by a plasma membrane and containing a membrane-bound nucleus...
		the center of the cell is the cell nucleus.
	www.animalsnpets.com /pets/animal-cell-nucleus.html (367 words)

	[No title] (Site not responding. Last check: )
		Archaea are, similarly to bacteria, single-celled organisms lacking cell nucleusnuclei and are therefore classified as prokaryotes known as Monera in the five kingdom taxonomy.
		The cells have several lobose pseudopods, with one large tubular pseudopod at the anterior and several secondary ones branching to the sides.
		Eukaryotic cells are usally found in multi-cellular organisms, while prokaryotic cells are usually on their own.
	www.worldhistory.com /wiki/c/cell-nucleus.htm (1065 words)

	Nucleus1
		Discusses the general functions of the cell nucleus and numerous other structures of the nucleus, including: the nuclear envelope, nuclear lamina, nuclear pore complex, active transport, signaling, and more.
		During cell division, the DNA becomes tightly wound around the histones to form structures called nucleosomes, which are further coiled and packaged into the highly condensed chromosome.
		The Cell Cycle and Mitosis Tutorial - An introduction to the cell cycle and to mitosis.
	darwin.nmsu.edu /~molbio/cell/Nucleus.html (760 words)

	Cell Nucleus Plant
		The basic plant cell has a similar construction to the animal cell, but does not have centrioles, lysosomes, cilia, or flagella.
		cell membrane - the thin layer of protein and fat that surrounds the cell, but is inside the cell wall.
		Chloe introduces you to her plant cell pals and shows you what they are made of...
	www.plants-n-seeds.com /10/cell-nucleus-plant.html (465 words)

	Cell Nucleus
		It is separated from the rest of the cell by the nuclear membrane.
		This seems to be continuous with a membrane inside the cell called the endoplasmic reticulum, and has pores which probably allow large molecules to move in and out of the nucleus.
		This is necessary since the messenger RNA which is made in the nucleus has to travel out into the rest of the cell so it can be used to direct the production of protein.
	www.historyoftheuniverse.com /cellnucl.html (170 words)

	Cell Nucleus (Site not responding. Last check: )
		In somatic cell nuclear transfer, researchers remove the nucleus of an egg and replace it with other cells, such as from a patient's skin.
		Similar to the cytoplasm of a cell, the nucleus contains nucleoplasm - a highly viscous solid containing the chromosomes and nucleoli.
		The nucleus, being the largest sub-cellular compartment, varies in diameter from 10 to 20 micrometres.
	www.wikiverse.org /cell-nucleus (337 words)

	Glossary [Stem Cell Information]
		The blastocyst is a sphere made up of an outer layer of cells (the trophoblast), a fluid-filled cavity (the blastocoel), and a cluster of cells on the interior (the inner cell mass).
		When it is used to refer to cells grown in a tissue culture dish, a clone is a line of cells that is genetically identical to the originating cell.
		By combining a patient's somatic cell nucleus and an enucleated egg, a scientist may harvest embryonic stem cells from the resulting embryo that can be used to generate tissues that match a patient's body.
	stemcells.nih.gov /info/glossary.asp (1853 words)

	What is a Cell
		The simplest of cells, and the first types of cells to evolve, were prokaryotic cells—organisms that lack a nuclear membrane, the membrane that surrounds the nucleus of a cell.
		The cells may be adjacent to one another because they did not separate after cell division or because they remained enclosed in a common sheath or slime secreted by the cells.
		All cells arise from pre-existing cells, that is, their genetic material must be replicated and passed from parent cell to progeny.
	www.ncbi.nlm.nih.gov /About/primer/genetics_cell.html (8545 words)

	Animal Cell Anatomy - EnchantedLearning.com
		Cells are covered by a cell membrane and come in many different shapes.
		During cell division (mitosis), the centrosome divides and the two parts move to opposite sides of the dividing cell.
		The nucleus is surrounded by the nuclear membrane.
	www.enchantedlearning.com /subjects/animals/cell/index.shtml (656 words)

	The nucleus ultrastructure
		Once spliced, RNA transcripts in some cases appear to exit the nucleus in a directed manner via tracks or paths that extend from the gene to the nuclear envelope, which suggests a highly organized and regulated means of transport of mRNA through the nucleoplasm to the nuclear pores.
		Such signals if present in the nucleus, may not be present in molecules like actin for instance, and perhaps for this and other reasons actin does not accumulate normally in the nucleus.
		The nucleus undergoes cyclic changes during cells reproduction, and is disassembled at late prophase and reassembled at telophase of cell division.
	www.som.tulane.edu /departments/pathology/fermin/Nucleusultrast.html (1835 words)

	Cell nucleus (Site not responding. Last check: )
		In cell biology, the nucleus (from Latin nucleus or nuculeus, kernel) is an organelle, found in all eukaryotic cells, which contains most of the cell's genetic material.
		Study of the function of the cell nucleus, and the nature, evolution, expression, recombination and segregation of the DNA sequences within the nucleus at interphase.
		Covers all aspects of receptor-based cell recognition and signaling: understanding of the molecular basis of cell behavior as influenced by the interaction of cells with one another and with the extracellular environment including extracellular matrix, cytokines and chemotactic factors.
	www.omniknow.com /common/wiki.php?in=en&term=Cell_nucleus (2047 words)

	Functional Architecture of the Cell Nucleus
		Despite the obvious importance of the cell nucleus as the genetic control center which regulates cellular growth and differentiation processes, there is still very little known about how the various steps of gene expression are spatially organized and integrated into nuclear structures.
		The cell nucleus is by far more than a collection of randomly distributed genes and diffusible transcription factors but rather represents a highly ordered structural entity with spatially organized chromosomes and functional territories in which synthesis, processing, packaging and transport of the gene products take place.
		A major goal of the program is to understand the complex pathway of gene expression within the structural framework of the cell nucleus, to elucidate the functional significance of nuclear structures and to identify topogenic sequences and signals of nucleic acids and nuclear proteins.
	www.innovations-report.com /html/reports/dfg_biology_medicine/report-3371.html (346 words)

	cell nucleus (web page)
		It is the brain of the cell and the center for direction and coordination of the cell's metabolic and reproductive activities.
		Cells with a nucleus are called eukaryotic cells becasue eukaryotic means, "possessing a true nucleus".
		The second is that the nucleus controls a cell's differentiation during the development of the metabolic activities of the cell.
	www.fresno.k12.ca.us /schools/S090/AtkinsGateBio/Eucaryotic/eucaryote6.htm (674 words)

	UB Department of Biological Sciences: Ronald Berezney
		Using combined structural, molecular, and computer imaging approaches, we are studying the functional organization, assembly, and cell cycle regulation of higher order units of replication, transcription and RNA splicing in the cell nucleus.
		We are investigating the 3-D organization and dynamics of chromosome territories, subchromosomal domains and individual genes in the interphase cell nucleus in relationship to replication, transcription and splicing factor domains.
		These include the genomic organization and regulation of nuclear matrin 3 and the analysis, nuclear assembly, cell cycle regulation, and functional properties of a recently discovered cyclophilin-type nuclear matrix protein, termed matrin cyp (cyclophilin), which co-localizes in three-dimensions with splicing component domains inside the cell nucleus.
	wings.buffalo.edu /academic/department/fnsm/bio-sci/faculty/berezney.html (665 words)

	Biologists: Cell nucleus surface more complicated than expected
		The researchers also found that the tunnels and folds in the cell nucleus contain cytoplasm and bundles of actin filaments, strings of protein along which organelles were observed moving in the nuclear grooves.
		Using the GFP to highlight chemical sequences associated with the endoplasmic reticulum, the researchers found that deep folds and grooves indented the surface of the nucleus, and that the endoplasmic reticulum actually passed through the center of the nucleus.
		Through dye-labeling experiments in untransformed onion epidermal and tobacco culture cells and through the expression of green fluorescent protein targeted to either the nucleus or the lumen of the endoplasmic reticulum/nuclear envelope in these cells, we have visualized deep grooves and invaginations into the large nuclei of these cells.
	www.eurekalert.org /pub_releases/2001-06/NCSU-BCns-1206101.php (1003 words)

	Cell Organelles: The Nucleus and Nucleolus
		When a cell is dividing, the DNA and surrounding protein condense into chromosomes (see photo) that are visible by microscopy.
		The prominent structure in the nucleus is the nucleolus.
		The nucleolus produces ribosomes, which move out of the nucleus to positions on the rough endoplasmic reticulum where they are critical in protein synthesis.
	www.cellsalive.com /cells/nucleus.htm (162 words)

	cell nucleus Dr.Jastrow's EM-Atlas
		Whereas the first 3 different cell types contain 3 to about 8 nuclei, the skeletal muscle cells possess some hundreds to a few thousand nuclei located close to the cell surface since some of them they are several millimetres long.
		The nuclear membrane separates the nucleus from the surrounding cell fluid with its organelles, the cytoplasm.
		cells of the pineal gland (pinealocytes) or transitorial epithelial cells of the urinary bladder.
	www.uni-mainz.de /FB/Medizin/Anatomie/workshop/EM/EMKernE.html (728 words)

	CancerQuest : Cell Structure : Nucleus
		The nucleus can be thought of as the brains of a cell.
		The nucleus (plural-nuclei) is roughly spherical and is surrounded by two membranes.
		Important in the development of cancer, small changes in the nucleotide sequence of a gene may result in the altered behavior of a cell.
	www.cancerquest.org /index.cfm?page=43 (188 words)

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