FACTOID # 17: Though Rhode Island is the smallest state in total area, it has the longest official name: The State of Rhode Island and Providence Plantations.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Small interfering RNA
Mediating RNA interference in cultured mammalian cells.

Small interfering RNA (siRNA), sometimes known as short interfering RNA or silencing RNA, are a class of 20-25 nucleotide-long double-stranded RNA molecules that play a variety of roles in biology. Most notably, siRNA is involved in the RNA interference (RNAi) pathway where the siRNA interferes with the expression of a specific gene. In addition to their role in the RNAi pathway, siRNAs also act in RNAi-related pathways, e.g. as an antiviral mechanism or in shaping the chromatin structure of a genome; the complexity of these pathways is only now being elucidated. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... A nucleotide is a chemical compound that consists of 3 portions: a heterocyclic base, a sugar, and one or more phosphate groups. ... For other uses, see RNA (disambiguation). ... 3D (left and center) and 2D (right) representations of the terpenoid molecule atisane. ... Cells use dicer to trim double stranded RNA to form small interfering RNA or microRNA. An exogenous dsRNA or endogenous pre-miRNA can be processed by dicer and incorporated into the RNA-induced silencing complex (RISC), which targets single-stranded messenger RNA molecules and triggers translational repression;[1] incorporation into... Gene expression, or simply expression, is the process by which the inheritable information which comprises a gene, such as the DNA sequence, is made manifest as a physical and biologically functional gene product, such as protein or RNA. Several steps in the gene expression process may be modulated, including the... vaghhyyyyyyyyyyyyyyyyyyyyyyyyyyyy viral vaghela (shrewsbury, massachusetts) also know as vagh is the hot sexy lover of kinjal shah (houston, texas) ... Chromatin is the complex of DNA and protein found inside the nuclei of eukaryotic cells. ... In biology the genome of an organism is the whole hereditary information of an organism that is encoded in the DNA (or, for some viruses, RNA). ...


siRNAs were first discovered by David Baulcombe's group in Norwich, England, as part of post-transcriptional gene silencing (PTGS) in plants, and published their findings in Science in a paper titled "A species of small antisense RNA in posttranscriptional gene silencing in plants".[1] Shortly thereafter, in 2001, synthetic siRNAs were then shown to be able to induce RNAi in mammalian cells by Thomas Tuschl and colleagues in a paper published in Nature.[2] This discovery led to a surge in interest in harnessing RNAi for biomedical research and drug development. David Baulcombe is a Plant Scientist with interests in genetic regulation, disease resistance and gene silencing. ... This article is about the English city. ... A micrograph of ongoing gene transcription of ribosomal RNA illustrating the growing primary transcripts. ... Gene silencing is a general term describing epigenetic processes of gene regulation. ... Science is the academic journal of the American Association for the Advancement of Science and is considered one of the worlds most prestigious scientific journals. ... Year 2001 (MMI) was a common year starting on Monday (link displays the 2001 Gregorian calendar). ... Nature is a prominent scientific journal, first published on 4 November 1869. ... Biomedical research (or experimental medicine), in general simply known as medical research, is the basic research or applied research conducted to aid the body of knowledge in the field of medicine. ... Drug development or preclinical development is defined in many pharmaceutical companies as the process of taking a new chemical lead through the stages necessary to allow it to be tested in human clinical trials, although a broader definition would encompass the entire process of drug discovery and clinical testing of...

Contents

Structure

siRNAs have a well defined structure: a short (usually 21-nt) double-strand of RNA (dsRNA) with 2-nt 3' overhangs on either end: A nucleotide is a chemical compound that consists of 3 portions: a heterocyclic base, a sugar, and one or more phosphate groups. ... For other uses, see RNA (disambiguation). ... A nucleotide is a chemical compound that consists of 3 portions: a heterocyclic base, a sugar, and one or more phosphate groups. ...


Image:SiRNA structure2.jpg Image File history File links Metadata No higher resolution available. ...


Each strand has a 5' phosphate group and a 3' hydroxyl (-OH) group. This structure is the result of processing by dicer, an enzyme that converts either long dsRNAs or small hairpin RNAs into siRNAs.[3] SiRNAs can also be exogenously (artificially) introduced into cells by various transfection methods to bring about the specific knockdown of a gene of interest. Essentially any gene of which the sequence is known can thus be targeted based on sequence complementarity with an appropriately tailored siRNA. This has made siRNAs an important tool for gene function and drug target validation studies in the post-genomic era. A phosphate, in inorganic chemistry, is a salt of phosphoric acid. ... // Hydroxyl group The term hydroxyl group is used to describe the functional group -OH when it is a substituent in an organic compound. ... One molecule of the Dicer protein from Giardia intestinalis, which catalyzes the cleavage of dsRNA to siRNAs. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... A short hairpin RNA (shRNA) is a sequence of RNA that makes a tight hairpin turn that can be used in gene expression silence. ... A gene knockdown, is a genetically modified organism that carries one or more genes in its chromosomes that has been made less active or had its expression reduced. ...


RNAi induction using siRNAs or their biosynthetic precursors

Dicer protein colored by protein domain.
Dicer protein colored by protein domain.

Transfection of an exogenous siRNA can be problematic, since the gene knockdown effect is only transient, particularly in rapidly dividing cells. One way of overcoming this challenge is to modify the siRNA in such a way as to allow it to be expressed by an appropriate vector, e.g. a plasmid. This is done by the introduction of a loop between the two strands, thus producing a single transcript, which can be processed into a functional siRNA. Such transcription cassettes typically use an RNA polymerase III promoter (e.g. U6 or H1), which usually direct the transcription of small nuclear RNAs (snRNAs) (U6 is involved in gene splicing; H1 is the RNase component of human RNase P). It is assumed (although not known for certain) that the resulting siRNA transcript is then processed by Dicer. Image File history File links Download high-resolution version (690x1164, 362 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): RNA interference Dicer ... Image File history File links Download high-resolution version (690x1164, 362 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): RNA interference Dicer ... --RAG 01:54, 16 March 2007 (UTC) The concept of the domain was first proposed in 1973 by Wetlaufer after X-ray crystallographic studies of hen lysozyme (Phillips, 1966), papain (Drenth et al. ... Transfection describes the introduction of foreign material into eukaryotic cells. ... Gene expression, or simply expression, is the process by which the inheritable information which comprises a gene, such as the DNA sequence, is made manifest as a physical and biologically functional gene product, such as protein or RNA. Several steps in the gene expression process may be modulated, including the... In epidemiology, a vector is an organism that does not cause disease itself but which spreads infection by conveying pathogens from one host to another. ... Figure 1: Illustration of a bacterium with plasmids enclosed showing chromosomal DNA and plasmids. ... A micrograph of ongoing gene transcription of ribosomal RNA illustrating the growing primary transcripts. ... RNA polymerase III (also called Pol III) transcribes DNA to synthesize ribosomal 5S rRNA, tRNA and other small RNAs. ... In genetics, splicing is a modification of genetic information after transcription, in which introns of precursor messenger RNA (pre-mRNA) are removed and exons of it are joined. ... Ribonuclease (RNase) is an enzyme that catalyzes the breakdown of RNA into smaller components. ... One molecule of the Dicer protein from Giardia intestinalis, which catalyzes the cleavage of dsRNA to siRNAs. ...


RNA activation

It has recently been found that dsRNA can also activate gene expression, a mechanism that has been termed "small RNA-induced gene activation" or RNAa. It has been shown that dsRNAs targeting gene promoters induce potent transcriptional activation of associated genes. RNAa was demonstrated in human cells using synthetic dsRNAs termed small activating RNAs (saRNAs). It is currently unknown if RNAa is conserved in other organisms.[4] Small double-stranded RNA (dsRNA) has been found to silence gene expression by an evolutionally conserved mechanism known as RNA interference or RNAi. ... Sarna may refer to father or son: Nahum Sarna, Bible Scholar Jonathan Sarna, Historian Category: ...


Challenges: Avoiding non-specific effects

RNAi intersects with a number of other pathways, so it is not surprising that on occasion non-specific effects are triggered by the experimental introduction of an siRNA. When a mammalian cell encounters a double-stranded RNA such as an siRNA, it may mistake it as a viral by-product and mount an immune response. Furthermore, since structurally related microRNAs modulate gene expression largely via incomplete complementarity with a target mRNA, unintended off-targeting may be effected by the introduction of an siRNA. In genetics, a miRNA (micro-RNA) is a form of single-stranded RNA which is typically 20-25 nucleotides long, and is thought to regulate the expression of other genes. ... The interaction of mRNA in a eukaryote cell. ...


Innate Immunity

Introduction of too much siRNA can result in non-specific events due to activation of innate immune responses. Most evidence to date suggest that this is probably due to activation of the dsRNA sensor PKR, although retinoic acid inducible Gene I (RIG-I) may also be involved. The induction of cytokines via Toll-like receptor 7 (TLR7) has also been described. One promising method of reducing the non-specific effects is to convert the siRNA into a microRNA. MicroRNAs occur naturally, and by harnessing this endogenous pathway it should be possible to achieve similar gene knockdown at comparatively low concentrations of resulting siRNAs. This should minimize non-specific effects. In genetics, a miRNA (micro-RNA) is a form of single-stranded RNA which is typically 20-25 nucleotides long, and is thought to regulate the expression of other genes. ...


Off-targeting

Off-targeting is another challenge facing siRNAs as a gene knockdown tool. Here, genes with incomplete complementarity are inadvertently downregulated by the siRNA (effectively, the siRNA acts as an miRNA), leading to problems in data interpretation and potential toxicity. This however can be partly addressed by designing appropriate control experiments, and siRNA design algorithms are currently being developed to produce siRNAs free from off-targeting. Genome-wide expression analysis, e.g. by microarray technology, can then be used to verify this and further refine the algorithms. A 2006 paper from the laboratory of Dr Khvorova implicates 6 or 7 basepairs long stretches from position 2 onwards in the siRNA matching with 3'UTR regions in off-targeted genes.[5] In genetics, a miRNA (micro-RNA) is a form of single-stranded RNA which is typically 20-25 nucleotides long, and is thought to regulate the expression of other genes. ...


Possible therapeutic applications and challenges

Given the ability to knockdown essentially any gene of interest, RNAi via siRNAs has generated a great deal of interest in both basic and applied biology. There are an increasing number of large-scale RNAi screens that are designed to identify the important genes in various biological pathways. As disease processes also depend on the activity of multiple genes, it is expected that in some situations turning off the activity of a gene with a siRNA could produce a therapeutic benefit.


However, applying RNAi via siRNAs to living animals, especially humans, poses many challenges. Experimentally siRNAs show different effectiveness in different cell types in a manner as yet poorly understood: some cells respond well to siRNAs and show a robust knockdown, while others show no such knockdown (even despite efficient transfection). Transfection describes the introduction of foreign material into eukaryotic cells. ...


Phase I results of the first two therapeutic RNAi trials (indicated for age-related macular degeneration, aka AMD) reported at the end of 2005, demonstrate that siRNAs are well tolerated and have suitable pharmacokinetic properties.[6] siRNAs and related RNAi induction methods therefore stand to become an important new class of drugs in the foreseeable future.[citation needed] This article or section should be merged with macular degeneration Treatment Those with AMD can sometimes benefit from the treatment tested in the Age-Related Eye Disease Study. ...


siRNAs in fiction

Ian McEwan's novel "Saturday" suggests an siRNA-based treatment for Huntington's disease. Ian McEwan CBE (born June 21, 1948) is a British novelist. ... The British hardcover edition, with the BT Tower in the background Saturday (2005) is a novel by the British author Ian McEwan that charts the day of a 48 year old London neurosurgeon called Henry Perowne. ...


See also

MicroRNA (miRNA) are a related class of gene regulatory small RNAs, typically 21-23nt in length. They typically differ from siRNA because they are processed from single stranded RNA precursors and show only partial complementarity to mRNA targets. They have been implicated in a wide range of functions such as cell growth and apoptosis, development, neuronal plasticity and remodeling, and even insulin secretion. miRNAs have also been implicated in disease: e.g. an overabundance of miRNA has been reported in cases of Fragile X Mental Retardation, while some cancers are associated with up- and downregulation of certain miRNA genes. In genetics, a miRNA (micro-RNA) is a form of single-stranded RNA which is typically 20-25 nucleotides long, and is thought to regulate the expression of other genes. ... Complementarity is a concept in a number of fields: Economics In economics is a concept similar to that of externality. ... Fragile X syndrome is a syndrome of X-linked mental retardation. ...


Initial studies have indicated that miRNAs regulate gene expression post-transcriptionally at the level of translational inhibition at P-bodies in the cytoplasm. However, miRNAs may also guide mRNA cleavage in a manner similar to siRNAs. This is often the case in plants where the target sites are typically highly complementary to the miRNA. While target sites in plant mRNAs can be found in the 5'UTR, open-reading frames and 3'UTR, in animals it is the 3' UTR that is the main target. This difference between plants and animals may be explained by their different modes of gene silencing. Also called GW or Dcp bodies, processing bodies are microscopic structures within the eukaryotic cell made up of many proteins and inactive mRNAs. ...


miRNAs are first transcribed as part of a primary microRNA (pri-miRNA). This is then processed by the Drosha with the help of Pasha/DGCR8 (=Microprocessor complex) into pre-miRNAs. The ~75nt pre-miRNA is then exported to the cytoplasm by exportin-5, where it is then diced into 21-23nt siRNA-like molecules by Dicer. In some cases, multiple miRNAs can be found on the pri-miRNA. Drosha is an RNase III enzyme responsible for initiating the processing of microRNA (miRNA), or short RNA molecules naturally expressed by the cell that regulate a wide variety of other genes by interacting with the RNA-induced silencing complex (RISC) to induce cleavage of complementary messenger RNA (mRNA). ... Pasha, also known as DGCR8, is a protein localized to the cell nucleus that is required for microRNA processing. ... Karyopherins are a group of proteins involved in transporting molecules through the nuclear pores of the nuclear envelope. ... One molecule of the Dicer protein from Giardia intestinalis, which catalyzes the cleavage of dsRNA to siRNAs. ...


Check out an illustrated advertorial on miRNA.[1]


References

  1. ^ Hamilton A, Baulcombe D (1999). "A species of small antisense RNA in posttranscriptional gene silencing in plants". Science 286 (5441): 950-2. PMID 10542148. 
  2. ^ Elbashir S, Harborth J, Lendeckel W, Yalcin A, Weber K, Tuschl T (2001). "Duplexes of 21-nucleotide RNAs mediate RNA interference in cultured mammalian cells". Nature 411 (6836): 494-8. PMID 11373684. 
  3. ^ Bernstein E, Caudy A, Hammond S, Hannon G (2001). "Role for a bidentate ribonuclease in the initiation step of RNA interference". Nature 409 (6818): 363-6. PMID 11201747. 
  4. ^ Li LC (2008). "Small RNA-Mediated Gene Activation", RNA and the Regulation of Gene Expression: A Hidden Layer of Complexity. Caister Academic Press. ISBN 978-1-904455-25-7. 
  5. ^ Birmingham A, Anderson E, Reynolds A, Ilsley-Tyree D, Leake D, Fedorov Y, Baskerville S, Maksimova E, Robinson K, Karpilow J, Marshall W, Khvorova A (2006). "3' UTR seed matches, but not overall identity, are associated with RNAi off-targets". Nat Methods 3 (3): 199-204. PMID 16489337. 
  6. ^ Tansey B. "Macular degeneration treatment interferes with RNA messages", San Francisco Chronicle, 11 August 2006. 

General background

  • Hannon G, Rossi J (2004). "Unlocking the potential of the human genome with RNA interference". Nature 431 (7006): 371-8. doi:10.1038/nature02870. PMID 15372045. 
  • Fire A, Xu S, Montgomery M, Kostas S, Driver S, Mello C (1998). "Potent and specific genetic interference by double-stranded RNA in Caenorhabditis elegans". Nature 391 (6669): 806-11. PMID 9486653.  The original paper by Fire et al. describing RNAi
  • Elbashir S, Lendeckel W, Tuschl T (2001). "RNA interference is mediated by 21- and 22-nucleotide RNAs". Genes Dev 15 (2): 188-200. PMID 11157775. 
  • Zamore P, Tuschl T, Sharp P, Bartel D (2000). "RNAi: double-stranded RNA directs the ATP-dependent cleavage of mRNA at 21 to 23 nucleotide intervals". Cell 101 (1): 25-33. PMID 10778853. 
  • Hamilton A, Baulcombe D (1999). "A species of small antisense RNA in posttranscriptional gene silencing in plants". Science 286 (5441): 950-2. PMID 10542148.  First description of siRNAs.

A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ...

Non-specific effects

  • Zhang Z, Weinschenk T, Guo K, Schluesener H (2006). "siRNA binding proteins of microglial cells: PKR is an unanticipated ligand". J Cell Biochem 97 (6): 1217-29. PMID 16315288. 
  • Kim D, Behlke M, Rose S, Chang M, Choi S, Rossi J (2005). "Synthetic dsRNA Dicer substrates enhance RNAi potency and efficacy". Nat Biotechnol 23 (2): 222-6. PMID 15619617. 
  • Sledz C, Williams B (2004). "RNA interference and double-stranded-RNA-activated pathways". Biochem Soc Trans 32 (Pt 6): 952-6. PMID 15506933. 
  • Pebernard S, Iggo R (2004). "Determinants of interferon-stimulated gene induction by RNAi vectors". Differentiation 72 (2-3): 103-11. PMID 15066190. 
  • Sledz C, Holko M, de Veer M, Silverman R, Williams B (2003). "Activation of the interferon system by short-interfering RNAs". Nat Cell Biol 5 (9): 834-9. PMID 12942087. 

External links

Tools for design and quality:

  • siRNA at Whitehead: A web-based siRNA Selection Program
  • Deqor: A web-based tool for the design and quality control of siRNAs
  • siDirect: a web-based online software system for designing siRNA sequences
  • siSearch: a siRNA design tool using a number of popular design methods
  • SpecificityServer: a tool for checking the specificity of a given siRNA
  • miRacle: tool for prediction of siRNA and microRNA targets using an algorithm which incorporates RNA secondary structure

Databases:

  • HuSiDa: Human siRNA Database
  • siRNAdb: a database of siRNA sequences

siRNA focused Companies:

  • Alnylam Pharmaceuticals
  • Anadys Pharmaceuticals
  • ArmaGen Technologies,Inc
  • BD Biosciences
  • Benitec
  • Bionomics
  • BioSpring
  • Celera Genomics
  • Cenix BioScience
  • Ceptyr
  • Ingenium Pharmaceuticals
  • Isis Pharmaceuticals
  • Nucleonics Inc
  • Pfizer Inc
  • RNAi Co.Ltd
  • Roche Kulmbach GmbH
  • Sigma-Aldrich
  • Sirna Therapeutics, Inc.
Look up nucleic acid in Wiktionary, the free dictionary. ... Adenine Guanine Thymine Cytosine ... Purine (1) is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring. ... For the programming language Adenine, see Adenine (programming language). ... Guanine is one of the five main nucleobases found in the nucleic acids DNA and RNA; the others being adenine, cytosine, thymine, and uracil. ... Pyrimidine is a heterocyclic aromatic organic compound similar to benzene and pyridine, containing two nitrogen atoms at positions 1 and 3 of the six-member ring [1]. It is isomeric with two other forms of diazine. ... Uracil is a pyrimidine which is common and naturally occurring. ... For the similarly-spelled vitamin compound, see Thiamine Thymine, also known as 5-methyluracil, is a pyrimidine nucleobase. ... Cytosine is one of the 5 main nucleobases used in storing and transporting genetic information within a cell in the nucleic acids DNA and RNA. It is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attached (an amine group at position 4 and a keto group at... Nucleosides are glycosylamines made by attaching a nucleobase (often reffered to simply as bases) to a ribose ring. ... Adenosine is a nucleoside composed of adenine attached to a ribose (ribofuranose) moiety via a β-N9-glycosidic bond. ... The chemical structure of adenosine Adenosine is a nucleoside formed when adenine is attached to a ribose ring (also known as a ribofuranose) via a β-N9-glycosidic bond. ... The chemical structure of Guanosine Guanosine is a nucleoside comprising guanine attached to a ribose (ribofuranose) ring via a β-N9-glycosidic bond. ... Guanosine is a molecule (known as a nucleoside) that is formed when guanine is attached to a ribose ring (also known as a ribofuranose) via a β-N9-glycosidic bond. ... Uridine is a molecule (known as a nucleoside) that is formed when uracil is attached to a ribose ring (also known as a ribofuranose) via a β-N1-glycosidic bond. ... The chemical structure of deoxythymidine Thymidine (more precisely called deoxythymidine can also be labelled deoxyribosylthymine, and thymine deoxyriboside) is a chemical compound, more precisely a pyrimidine deoxynucleoside. ... Cytidine is a molecule (known as a nucleoside) that is formed when cytosine is attached to a ribose ring (also known as a ribofuranose) via a β-N1-glycosidic bond. ... Cytidine is a molecule (known as a nucleoside) that is formed when cytosine is attached to a ribose ring (also known as a ribofuranose) via a β-N1-glycosidic bond. ... A nucleotide is a chemical compound that consists of 3 portions: a heterocyclic base, a sugar, and one or more phosphate groups. ... Adenosine monophosphate, also known as 5-adenylic acid and abbreviated AMP, is a nucleotide that is found in RNA. It is an ester of phosphoric acid with the nucleoside adenosine. ... Guanosine monophosphate, also known as 5-guanidylic acid and abbreviated GMP, is a nucleotide that is found in RNA. It is an ester of phosphoric acid with the nucleoside guanosine. ... Uridine monophosphate, also known as 5-uridylic acid and abbreviated UMP, is a nucleotide that is found in RNA. It is an ester of phosphoric acid with the nucleoside uridine. ... Cytidine monophosphate, also known as 5-cytidylic acid and abbreviated CMP, is a nucleotide that is found in RNA. It is an ester of phosphoric acid with the nucleoside cytidine. ... Adenosine diphosphate, abbreviated ADP, is a nucleotide. ... Uridine diphosphate, abbreviated UDP, is a nucleotide. ... Cytidine diphosphate, abbreviated CDP, is a nucleotide. ... Adenosine 5-triphosphate (ATP) is a multifunctional nucleotide that is most important as a molecular currency of intracellular energy transfer. ... Guanosine triphosphate (GTP) is also known as guanosine-5-triphosphate. ... Adenosine 5-triphosphate (ATP) is a multifunctional nucleotide primarily known in biochemistry as the molecular currency of intracellular energy transfer. ... Cytidine triphosphate is a pyrimidine nucleotide. ... Structure of cAMP cAMP represented in three ways, the left with sticks-representation, the middle with structure formula, and the right with space filled representation. ... Cyclic guanosine monophosphate (cGMP) is a second messenger derived from GTP. Cyclic guanosine monophosphate (cGMP) is a cyclic nucleotide derived from guanosine triphosphate (GTP). ... Cyclic ADP Ribose popularly known as cADPR is a cyclic adenine nucleotide (like cAMP) with two phosphate groups present on 5 OH of the adenosine (like ADP), further connected to another ribose at the 5 position which in turn closes the cycle by glycosidic bonding to the Nitrogen1 of the... A nucleotide is a monomer or the structural unit of nucleotide chains forming nucleic acids as RNA and DNA. A nucleotide consists of a heterocyclic nucleobase, a pentose sugar, and a phosphate or polyphosphate group. ... This article belongs in one or more categories. ... Deoxyguanosine monophosphate is a derivative of the common nucleic acid GTP, or guanosine triphosphate, in which the -OH (hydroxyl) group on the 2 carbon on the nucleotides pentose has been reduced to just a hydrogen atom (hence the deoxy- part of the name). ... Thymidine monophosphate, also known as 5-thymidylic acid and abbreviated TMP, is a nucleotide that is found in RNA. It is an ester of phosphoric acid with the nucleoside thymidine. ... Deoxycytidine monophosphate is a deoxynucleotide, and one of the four monomers that make up DNA. In a DNA double helix, it will base pair with deoxyguanosine monophosphate. ... Deoxyadenosine diphosphate is a derivative of the common nucleic acid ATP, or adenosine triphosphate, in which the -OH (hydroxyl) group on the 2 carbon on the nucleotides pentose has been removed (hence the deoxy- part of the name). ... Deoxyguanosine diphosphate is a derivative of the common nucleic acid GTP, or guanosine triphosphate, in which the -OH (hydroxyl) group on the 2 carbon on the nucleotides pentose has been removed (hence the deoxy- part of the name). ... Thymidine diphosphate, abbreviated TDP, is a nucleotide. ... Please wikify (format) this article or section as suggested in the Guide to layout and the Manual of Style. ... Deoxy adenosine triphosphate produces energy within the cells and is the basis for normal functioning of all body systems and organs. ... The chemical structure of dGTP Deoxyguanosine triphosphate, normally shortened to dGTP has a chemical structure of Na4 â€¢ 3 H2O and a molecular weight of 649. ... 3D-Model of thymidine triphosphate Thymidine triphosphate or TTP is one of the four nucleoside triphosphates that make up DNA. It can be used by DNA ligase to create overlapping sticky ends so that protruding ends of opened microbial plasmids maybe closed up. ... This article or section is in need of attention from an expert on the subject. ... For other uses, see RNA (disambiguation). ... For other uses, see RNA (disambiguation). ... The life cycle of an mRNA in a eukaryotic cell. ... Precursor mRNA, more commonly termed pre-mRNA, is an incompletely processed single strand of messenger ribonucleic acid (mRNA), synthesized from a DNA template in the nucleus of a cell by transcription. ... Transfer RNA Transfer RNA (abbreviated tRNA), first hypothesized by Francis Crick, is a small RNA chain (73-93 nucleotides) that transfers a specific amino acid to a growing polypeptide chain at the ribosomal site of protein synthesis during translation. ... Ribosomal RNA (rRNA), a type of RNA synthesized in the nucleolus by RNA Pol I, is the central component of the ribosome, the protein manufacturing machinery of all living cells. ... Antisense mRNA is an mRNA transcript that is complementary to endogenous mRNA. It is the noncoding strand complementary to the coding sequence of mRNA. Introducing a transgene coding for antisense mRNA is a strategy used to block expression of a gene of interest. ... Guide RNA (gRNA) is a type of RNA that is used in mRNA editing. ... The stem-loop secondary structure of a pre-microRNA from Brassica oleracea. ... A non-coding RNA (ncRNA) is any RNA molecule that is not translated into a protein. ... Piwi-interacting RNA (piRNA) is a class of small RNA molecules that is expressed uniquely in mammalian testes and forms RNA-protein complexes with Piwi proteins. ... A short hairpin RNA (shRNA) is a sequence of RNA that makes a tight hairpin turn that can be used in gene expression silence. ... A non-coding RNA (ncRNA) is any RNA molecule that functions without being translated into a protein. ... A non-coding RNA (ncRNA) is any RNA molecule that is not translated into a protein. ... A non-coding RNA (ncRNA) is any RNA molecule that functions without being translated into a protein. ... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... In genetics, complementary DNA (cDNA) is DNA synthesized from a mature mRNA template. ... gDNA is the abbreviation of the term Genomic Deoxyribonucleic acid. ... An example of an RNA stem-loop, similar to what is seen in the RNA region of msDNA Multicopy single-stranded DNA (msDNA) is a type of extrachromosomal satellite DNA which consists of a single-stranded DNA molecule linked via a phosphodiester bond to a branched RNA molecule. ... Mitochondrial DNA (some captions in German) Mitochondrial DNA (mtDNA) is the DNA located in organelles called mitochondria. ... Nucleic acid analogues are compounds structurally similar to naturally occuring RNA and DNA, used as a research tool in molecular biology and/or as cure in medicine. ... Glycerol nucleic acid (GNA) is a chemical similar to DNA or RNA but differing in the composition of its backbone. GNA is not known to occur naturally in existing life on Earth. ... A locked nucleic acid (LNA) is a modified RNA nucleotide. ... PNA can also refer to the Palestinian National Authority or Pakistan National Alliance. ... TNA is threose nucleic acid, a chemical similar to DNA or RNA but differing in the composition of its backbone. ... Segment of a Morpholino-RNA heteroduplex, 8-mer shown In molecular biology, a Morpholino is a kind of molecule used to modify gene expression. ... The pGEX-3x plasmid is a popular cloning vector. ... A phagemid is a type of cloning genetics vector developed as a co-infection of the M13 helper phage and plasmids to produce a smaller version of the virus. ... Figure 1: Illustration of a bacterium with plasmids enclosed showing chromosomal DNA and plasmids. ... Enterobacteria phage λ (lambda phage) is a temperate bacteriophage that infects Escherichia coli. ... A cosmid is a type of plasmid (often used as a cloning vector) constructed by the insertion of cos sequences, DNA-Sequences of the Phage Lambda Virus. ... P1 is a temperate bacteriophage (phage). ... A bacterial artificial chromosome (BAC) is a DNA construct, based on a fertility plasmid (or F-plasmid), used for transforming and cloning in bacteria, usually E. coli. ... A yeast artificial chromosome (short YAC) is a vector used to clone large DNA fragments (larger than 100 kb and up to 3000 kb). ... A human artificial chromosome (short HAC) is a microchromosome that can act as a new chromosome in a population of human cells. ... Biochemistry (from Greek: , bios, life and Egyptian kÄ“me, earth[1]) is the study of the chemical processes in living organisms. ... Peptides (from the Greek πεπτος, digestible), are the family of short molecules formed from the linking, in a defined order, of various α-amino acids. ... This article is about the class of chemicals. ... Look up nucleic acid in Wiktionary, the free dictionary. ... Lactose is a disaccharide found in milk. ... Nucleotide sugars are biochemicals that act as donors of sugar residues in nucleotide sugars metabolism. ... Some common lipids. ... Many terpenes are derived from conifer resins, here a pine. ... The orange ring surrounding Grand Prismatic Spring is due to carotenoid molecules, produced by huge mats of algae and bacteria. ... Polypyrrole A Polypyrrole (PPy) is a chemical compound formed from a number of connected pyrrole ring structures. ... A cofactor is any substance that needs to be present in addition to an enzyme to catalyze a certain reaction. ... This article is about the chemical family of steroids. ... Molecular structure of the flavone backbone (2-phenyl-1,4-benzopyrone) The term flavonoid refers to a class of plant secondary metabolites. ... Chemical structure of ephedrine, a phenethylamine alkaloid An alkaloid is a nitrogen-containing naturally occurring compound, produced by a large variety of organisms, including fungi, plants, animals, and bacteria. ... Polyketides are secondary metabolites from bacteria, fungi, plants, and animals. ... A glycoside is a molecule where a sugar group is bonded through its anomeric carbon to a nonsugar group by either an oxygen or a nitrogen atom. ...

  Results from FactBites:
 
Altogen Biosystems - Transfection Resource (2301 words)
RNA interference (RNAi) is a phenomenon by which the expression of double stranded RNA (dsRNA) specifically stimulates a cellular process that reduces gene expression in a sequence specific manner.
Potent inhibition of specific gene expression is experimentally achieved by the transfection of small interfering RNA (siRNA), which binds RISC complex and cause degradation of target complementary mRNA molecules in the cell.
Small RNA molecules, such as siRNA, shRNA, and microRNA have been regarded as potential therapeutic agents to target multiple misregulated cellular processes therefore it is theoretically possible that RNAi can be utilized to treat any disease associated with overexpression of specific genes.
Small interfering RNA - Wikipedia, the free encyclopedia (600 words)
Small interfering RNA (siRNA), sometimes known as short interfering RNA, are a class of 20-25 nucleotide-long RNA molecules that interfere with the expression of genes.
They are naturally produced as part of the RNA interference (RNAi) pathway by the enzyme Dicer.
RNA interference is mediated by 21- and 22-nucleotide RNAs
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m