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Encyclopedia > Overexpression

Gene expression (also protein expression or often simply expression) is the process by which a gene's information is converted into the structures and functions of a cell.


Gene expression is a multi-step process that begins with In genetics, transcription is the first of the two-step protein biosynthesis process. Transcription is an enzymatic process that reads DNA and transforms it into its complementary RNA sequence. Transcription ultimately leads to DNA translation. There is no proofreading or correction process; therefore, it has a lower copying fidelity then... transcription and Translation in the cytoplasm; tRNA carries amino acids which are added to the growing peptide chain in the ribosome. Translation is the second process of protein biosynthesis (part of the overall process of gene expression). In translation, messenger RNA is decoded to produce a specific polypeptide according to the rules... translation and is followed by Protein folding is the process by which a protein assumes its functional shape or conformation. All protein molecules are simple unbranched chains of amino acids, but it is by coiling into a specific three-dimensional shape that they are able to perform their biological function. In fact, disruption of the... folding, Posttranslational modification means the chemical modification of a protein after its translation. It is one of the later steps in protein biosynthesis for many proteins. Posttranslational modification may involve the formation of disulfide bridges and attachment of any of a number of biochemical functional groups, such as acetate, phosphate, various... post-translational modification and Protein targeting includes the mechanisms by which a biological cell transports proteins to the appropriate organelle for insertion into a membrane or secretion to the outside. (This article deals with protein targeting in eukaryotes except as noted.) Protein translocation In 1970, G√ľnter Blobel conducted experiments on the translocation of... targeting. The amount of protein that a Cells in culture, stained for keratin The cell is the structural and functional unit of all living organisms. Some organisms, such as bacteria, are unicellular, consisting of a single cell. Other organisms, such as humans, are multicellular, (humans have an estimated 100,000 billion = 1014 cells). The cell theory, first... cell expresses depends on the Biological tissue is a group of cells that perform a similar function. The study of tissues is known as histology, or, in connection with disease, histopathology. The classical tools for studying the tissues are the wax block, the tissue stain, and the optical microscope, though developments in electron microscopy, immunofluorescence... tissue, the In Developmental psychology, a stage is a distinct phase in an individuals development. Many theories in psychology characterize development in terms of stages. Eriksons stages of psychosocial development. Developed by Erik Erikson to describe how individuals relate to their social world. Kohlbergs stages of moral development. Developed... developmental stage of the In biology and ecology, an organism (in Greek organon = instrument) is a living being. The origin of life and the relationships between its major lineages are controversial. Two main grades may be distinguished, the prokaryotes and eukaryotes. The prokaryotes are generally considered to represent two separate domains, called the Bacteria... organism and the metabolic or physiologic state of the cell.

Contents

Measurement

Indirectly, the expression of particular genes may be assessed with A DNA microarray, the different colours indicate relative expression of different genes. A DNA microarray is a collection of microscopic DNA spots attached to a solid surface, such as glass, plastic or silicon chip forming an array. Scientists use DNA microarrays to measure the expression levels of large numbers of... DNA microarray technology, which can provide a rough measure of the cellular This page refers to concentration in the chemical sense. For the psychological concept of concentration, see attention. For the game show of the same name, see concentration (game show). Concentration is a very common concept used in chemistry and related fields. It is the measure of how much of a... concentration of different mRNAs; often thousands at a time. While the name of this type of assessment is actually a misnomer, it is often referred to as expression profiling. (The expression of many genes is known to be regulated after transcription, so an increase in mRNA concentration need not always increase expression.)


Control of expression

Control of gene expression depends various factors including:

  • This article is about the biological chromosome. For information about chromosomes in genetic algorithms, see Chromosome (genetic algorithm). Figure 1: Chromosome. (1) Chromatid. One of the two identical parts of the chromosome after S phase. (2) Centromere. The point where the two chromatids touch, and where the microtubules attach. (3... chromosomal activation or deactivation.
  • Control of initiation of In genetics, transcription is the first of the two-step protein biosynthesis process. Transcription is an enzymatic process that reads DNA and transforms it into its complementary RNA sequence. Transcription ultimately leads to DNA translation. There is no proofreading or correction process; therefore, it has a lower copying fidelity then... transcription
  • Processing of Ribonucleic acid (RNA) is a nucleic acid consisting of a string of covalently-bound nucleotides. It is biochemically distinguished from DNA by the presence of an additional hydroxyl group, attached to each pentose ring; as well as by the use of uracil, instead of thymine. One of the main functions... RNA (ie. In genetics, splicing is a modification of genetic information prior to translation. In eukaryotes, a gene often contains altering sequences known as exons and introns. In contrast to prokaryotes, which do not have introns, the primary mRNA transcript called pre-mRNA (see transcription) from the DNA has to be spliced... splicing)
  • Control of RNA transport.
  • Control of The interaction of mRNA in a eukaryote cell. RNA is created in the transcription; after splicing and polyadenylation it is transported to the cytoplasm, and translation occurs in a ribosome. Messenger RNA (mRNA) is RNA that carries information from DNA to the ribosome sites of protein synthesis in the cell... mRNA degradation.
  • Control of initiation of Translation in the cytoplasm; tRNA carries amino acids which are added to the growing peptide chain in the ribosome. Translation is the second process of protein biosynthesis (part of the overall process of gene expression). In translation, messenger RNA is decoded to produce a specific polypeptide according to the rules... translation (only in Kingdoms Eukaryotes are organisms with complex cells, in which the genetic material is organized into membrane-bound nuclei. They include the animals, plants, and fungi, which are mostly multicellular, as well as various other groups called protists, many of which are unicellular. In contrast, other organisms such as bacteria lack... eukaryotes)
  • Posttranslational modification means the chemical modification of a protein after its translation. It is one of the later steps in protein biosynthesis for many proteins. Posttranslational modification may involve the formation of disulfide bridges and attachment of any of a number of biochemical functional groups, such as acetate, phosphate, various... Post-translational modifications.

Overexpression

The protein encoded for by a gene can be expressed in increased quantity. This can come about by:

  • increasing the number of copies of the gene
  • increasing the binding strength of the promoter region

Often, the DNA sequence for a protein of interest will be spliced into a Figure 1 : Schematic drawing of a bacterium with plasmids enclosed. (1) Chromosomal DNA. (2) Plasmids Plasmids are (typically) circular double stranded DNA molecules that are separate from the chromosomal DNA (Fig. 1). They usually occur in bacteria, sometimes in eukaryotic organisms (e.g., the 2-micrometre-ring in Saccharomyces... plasmid containing the The lac operon is a DNA sequence that governs the production of proteins and enzymes for transporting and metabolizing lactose in bacteria such as E. coli. In the absence of lactose, the lac repressor substance binds to the operator (a part of the DNA sequence), inhibiting the production of three... lac promoter and used for Transformation has two meanings in molecular biology: Transformation is the genetic alteration of a cell resulting from the introduction, uptake and expression of foreign DNA. Transformation is also the process by which normal cells are converted into cells that will continue to divide without limit. Normal cells can divide only... transformation of bacteria. Addition of IPTG (a Lactose is the sugar making up around 2-8% of the solids in milk. The name comes from the Latin for milk, plus the -ose ending used to name sugars. Lactose is a disaccharide consisting of two subunits, a galactose and a glucose linked together. Its empirical formula is C12H22O11... lactose analog) causes the bacteria to produce ( For other meanings, see Dictionary definition of Express. Express is an American clothing company owned by Limited Brands. Express was predominantly a womens clothing company. However in early 2000, the Structure (another Limited Brands company) was realigned into ExpressMen. External links Express Fashion Limited Brands Categories: Corporation stubs | Clothing... express)the protein of interest. It doesn't work with every protein (sometimes Saccharomyces cerevisiae is a yeast used in both baking and brewing. Yeast is a group of single Celled fungi a few species of which are commonly used to leaven bread and ferment alcoholic beverages. Most yeasts belong to the division Ascomycota. A few yeasts, such as Candida albicans can cause... yeast do a better job with post-translational modifications), but bacterial expression can sometimes be used to make a lot of protein with minimal fuss, for example for X-ray crystallography is a technique in crystallography in which the pattern produced by the diffraction of x-rays through the closely spaced lattice of atoms in a crystal is recorded and then analyzed to reveal the nature of that lattice. The spacings in the crystal lattice can be determined... X-ray crystallography or NMR may refer to: Nuclear magnetic resonance, a phenomenon involving the interaction of atomic nuclei and external magnetic fields Nielsen Media Research, a U.S. company which measures TV, radio and newspaper audiences This is a disambiguation page — a navigational aid which lists other pages that might otherwise share... NMR structure determination.


Gene networks and expression

Main article: A gene regulatory network (also called a GRN or genetic regulatory network) is a collection of DNA segments in a cell which interact with each other and with other substances in the cell, thereby governing the rates at which genes in the network are transcribed into mRNA. Overview Genes can... Gene regulatory network


Genes have sometimes been regarded as nodes in a network, with inputs being proteins such as In molecular biology, a transcription factor is a protein that binds DNA at a specific promoter or enhancer region or site, where it regulates transcription. Transcription factors can be selectively activated or deactivated by other proteins, often as the final step in signal transduction. Classes There are three classes of... transcription factors, and outputs being the level of gene expression. The node itself performs a function, these and the operation of these functions have been interpreted as performing a kind In general, information processing is the changing (processing) of information in any manner detectable by an observer. As such, it is a process which describes everything which happens (changes) in the universe, from the falling of a rock (a change in position) to the printing of a text file from... information processing within cell and determine cellular behaviour.


See also

  • An expressed sequence tag or EST is a short sub-sequence of a protein-coding DNA sequence. It was originally intended as a way to identify gene transcripts, but has since been instrumental in gene discovery and sequence determination. An EST is produced by one-shot sequencing of a cloned... Expressed sequence tag

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