Get flash to fully experience Pearltrees
A 3D representation of the lysine riboswitch In molecular biology , a riboswitch is a regulatory segment of a messenger RNA molecule that binds a small molecule , resulting in a change in production of the proteins encoded by the mRNA. [ 1 ] [ 2 ] [ 3 ] [ 4 ] Thus, an mRNA that contains a riboswitch is directly involved in regulating its own activity, in response to the concentrations of its effector molecule. The discovery that modern organisms use RNA to bind small molecules, and discriminate against closely related analogs, expanded the known natural capabilities of RNA beyond its ability to code for proteins , catalyze reactions , or to bind other RNA or protein macromolecules . The original definition of the term "riboswitch" specified that they directly sense small-molecule metabolite concentrations. [ 5 ] Although this definition remains in common use, some biologists have used a broader definition that includes other cis-regulatory RNAs .
Structure of an RNA aptamer specific for biotin . The aptamer surface and backbone are shown in yellow. Biotin (spheres) fits snugly into a cavity of the RNA surface Aptamers (from the Latin aptus - fit, and Greek meros - part) are oligonucleic acid or peptide molecules that bind to a specific target molecule. Aptamers are usually created by selecting them from a large random sequence pool, but natural aptamers also exist in riboswitches . Aptamers can be used for both basic research and clinical purposes as macromolecular drugs.
From Wikipedia, the free encyclopedia Cassette may refer to: In general, a small Cartridge . It may refer specifically to: Compact Cassette , a worldwide standard for analog audio recording and playback, also known as audio cassette , cassette tape , or tape Digital Audio Tape (or DAT ), a digital audio cassette tape format, mainly used by professionals Digital Compact Cassette (or DCC ), a short-lived digital audio cassette format aimed at domestic users Videocassette , a cassette containing videotape, for use in VCRs Data cassette , magnetic tape in plastic housing Album (Public Image Ltd album) , a 1986 Public Image Ltd album called "Cassette" on certain editions Cassette , a set of multiple sprockets on a bicycle Cassette (New Zealand band) , a band from New Zealand Cassette (South African band) , a band from South Africa.
A renewable resource is a natural resource which can replenish with the passage of time, either through biological reproduction or other naturally recurring processes. Renewable resources are a part of Earth 's natural environment and the largest components of its ecosphere . A positive life cycle assessment is a key indicator of a resource's sustainability . In 1962, Paul Alfred Weiss defined Renewable Resources as: " The total range of living organisms providing man with food, fibers, drugs, etc... ". [ 1 ] Renewable resources may be the source of power for renewable energy . However, if the rate at which the renewable resource is consumed exceeds its renewal rate, renewal and sustainability will not be ensured.
A tool is any physical item that can be used to achieve a goal , especially if the item is not consumed in the process. Informally the word is also used to describe a procedure or process with a specific purpose. Tool use by humans dates back millions of years, and other animals are also known to employ simple tools. Tools that are used in particular fields or activities may have different designations such as "instrument", "utensil", "implement", "machine", or "apparatus". The set of tools needed to achieve a goal is "equipment".
A scanning electron microscope image of NETs engulfing fungal cells ( Candida albicans ) in an infected mouse lung. (Click on image for more details). Neutrophil extracellular traps ( NETs ) are networks of extracellular fibers, primarily composed of DNA from neutrophils , which bind pathogens . [ 1 ] It has long been known that neutrophils (our front-line of defence against infection) use two strategies to kill invading pathogens: engulfment of microbes and secretion of anti-microbials.
A training set is a set of data used in various areas of information science to discover potentially predictive relationships. Training sets are used in artificial intelligence , machine learning , genetic programming , intelligent systems , and statistics . In all these fields, a training set has much the same role and is often used in conjunction with a test set . [ edit ] Use in artificial intelligence, machine learning, and statistics
Carnosine should not be confused with Carnitine . Carnosine ( beta -alanyl-L-histidine) is a dipeptide of the amino acids beta-alanine and histidine . It is highly concentrated in muscle and brain tissues . Carnosine and carnitine were discovered by Russian chemist V.Gulevich. [ 2 ] Researchers in Britain, [ 3 ] South Korea, [ 4 ] Russia [ 5 ] [ 6 ] and other countries [ 7 ] [ 8 ] [ 9 ] have shown that carnosine has a number of antioxidant properties that may be beneficial. Carnosine has been proven to scavenge reactive oxygen species (ROS) as well as alpha-beta unsaturated aldehydes formed from peroxidation of cell membrane fatty acids during oxidative stress .
Glycolysis overview Glycolysis (from glycose , an older term [ 1 ] for glucose + -lysis degradation) is the metabolic pathway that converts glucose C 6 H 12 O 6 , into pyruvate , CH 3 COCOO − + H + . The free energy released in this process is used to form the high-energy compounds ATP ( adenosine triphosphate ) and NADH ( reduced nicotinamide adenine dinucleotide ). [ 2 ] Glycolysis is a determined sequence of ten reactions involving ten intermediate compounds (one of the steps involves two intermediates). The intermediates provide entry points to glycolysis. For example, most monosaccharides, such as fructose , glucose , and galactose , can be converted to one of these intermediates.
The person having ordinary skill in the art (often abbreviated PHOSITA in the United States ), the person of ordinary skill in the art , the skilled addressee , person skilled in the art or simply the skilled person is a legal fiction found in many patent laws throughout the world. This fictional person is considered to have the normal skills and knowledge in a particular technical field, without being a genius. He or she mainly serves as a reference for determining, or at least evaluating, whether an invention is non-obvious or not (in US patent law), or does involve an inventive step or not (in European patent laws). If it would have been obvious for this fictional person to come up with the invention while starting from the prior art , then the particular invention is considered not patentable .
Broadly, a citation is a reference to a published or unpublished source (not always the original source). More precisely, a citation is an abbreviated alphanumeric expression (e.g. [Newell84]) embedded in the body of an intellectual work that denotes an entry in the bibliographic references section of the work for the purpose of acknowledging the relevance of the works of others to the topic of discussion at the spot where the citation appears. Generally the combination of both the in-body citation and the bibliographic entry constitutes what is commonly thought of as a citation (whereas bibliographic entries by themselves are not).
See Conjecture (San Diego Convention) for the annual science fiction convention held in and around San Diego, California in the fall/autumn. A conjecture is a proposition that is unproven . Karl Popper pioneered the use of the term "conjecture" in scientific philosophy . [ 1 ] Conjecture is contrasted by hypothesis (hence theory , axiom , principle ), which is a testable statement based on accepted grounds.
A postmark on a letter, with a timestamp showing the date (center) and time the letter was received by the post office. German date and time stamp, a rubber stamp that stamps the current date and time on a document, 1960s Advertisement for a 1915 camera, that stamped the time each picture was taken in ink on the picture. A timestamp is a sequence of characters or encoded information identifying when a certain event occurred, usually giving date and time of day, sometimes accurate to a small fraction of a second.
In computational complexity theory , a probabilistically checkable proof ( PCP ) is a type of proof that can be checked by a randomized algorithm using a bounded amount of randomness and reading a bounded number of bits of the proof. The algorithm is then required to accept correct proofs and reject incorrect proofs with very high probability. A standard proof (or certificate ), as used in the verifier -based definition of the complexity class NP , also satisfies these requirements, since the checking procedure deterministically reads the whole proof, always accepts correct proofs and rejects incorrect proofs.
An autocatalytic set is a collection of entities, each of which can be created catalytically by other entities within the set, such that as a whole, the set is able to catalyze its own production. In this way the set as a whole is said to be autocatalytic . Autocatalytic sets were originally and most concretely defined in terms of molecular entities , but have more recently been metaphorically extended to the study of systems in sociology and economics .