Science terms starting with R

652 terms

restriction fragment A shortened DNA molecule generated by the cleavage of a larger molecule by one or more restriction endonucleases.
restriction fragment length polymorphism (Abbreviation: RFLP). A class of genetic marker based on the detection of variation in the length of restriction fragments generated when DNA is treated…
Restriction fragment length polymorphism (RFLP) Differences in nucleotide sequence between alleles at a chromosomal locus result in restriction fragments of varying lengths detected by Southern analysis.
Restriction map See Mapping.
restriction site Synonym of recognition site.
Restriction-enzyme cutting site A specific nucleotide sequence of DNA at which a particular restriction enzyme cuts the DNA. Some sites occur frequently in DNA (e.g.
Restructuring The process of changing the structure of the electric power industry from one of guaranteed monopoly over service territories, as established by the…
Retail unbundling Disaggregating electric utility service into its basic components and offering each component separately for sale with separate rates for each component.
Retail Wheeling A term for the process of transmitting electricity over transmission lines not owned by the supplier of the electricity to a retail customer of the…
Retaining wall A wall separating two levels.
reticulocyte A slightly immature red blood cell.
Retinal damage Damage to photoreceptor cells of the retina. One mechanism for such damage is exposure to bright light that triggers chemical reactions in the tissues…
Retinoic acid (REH-tih-NOH-ik A-sid) A form of vitamin A that is made by the body, and can also be made in the laboratory.
retro-element Any of the integrated retrovirus es or the transposable elements that resemble them.
Retrofit The process of modifying a building's structure.
Retrofitting The application of conservation, efficiency, or renewable energy technologies to existing structures.
Retrogression (or Retrograde Motion) - Movement of a weather system in a direction opposite to that of the basic flow in which it is embedded, usually referring to a…
retroposon A transposable element that moves via reverse transcription but lacks the long terminal repeat sequences necessary for autonomous transposition.
Retroviral infection The presence of retroviral vectors, such as some viruses, which use their recombinant DNA to insert their genetic material into the chromosomes of the…
retroviral vectors Gene transfer systems based on viruses that have RNA as their genetic material.
retrovirus (REH-troh-VY-rus) A type of virus that has RNA instead of DNA as its genetic material.
Return Air Air that is returned to a heating or cooling appliance from a heated or cooled space.
Return Duct The central heating or cooling system contains a fan that gets its air supply through these ducts, which ideally should be installed in every room of the…
Return Flow Drainage water from irrigated farmlands that re-enters the water system to be used further downstream.
Return on investment (ROI) The interest rate at which the net present value of a project is zero. Multiple values are possible.
Return Stroke An electrical discharge that propagates upward along a lightning channel from the ground to the cloud.
Return-flow system (reuse system) A system of pipelines or ditches to collect and convey surface or subsurface runoff from an irrigated field for reuse.
Reuse The reclamation of water diverted from a municipal or industrial wastewater conveyance system.
reversal transfer Transfer of a culture from a callus-supporting medium to a shoot-inducing medium.
Reverse genetics Using linkage analysis and polymorphic markers to isolate a disease gene in the absence of a known metabolic defect, then using the DNA sequence of the…
reverse mutation See: reversion.
Reverse Thermosiphoning When heat seeks to flow from a warm area (e.g., heated space) to a cooler area, such as a solar air collector at night without a reverse flow damper.
Reverse transcriptase An enzyme that uses an RNA molecule as a template for the synthesis of a complementary DNA strand. Synonym: RNA -dependent DNA polymerase.
Reverse transcriptase (RNA-dependent DNA polymerase) An enzyme isolated from retrovirus-infected cells that synthesizes a complementary (c)DNA strand from an RNA template.
reverse transcription (ree-VERS tran-SKRIP-shun) In biology, the process in cells by which an enzyme makes a copy of DNA from RNA.
Reversing Valve A component of a heat pump that reverses the refrigerant's direction of flow, allowing the heat pump to switch from cooling to heating or heating to…
reversion Restitution of a mutant gene to the wild-type condition, or at least to a form that gives the wild-type phenotype; more generally, the appearance of a…
Revetment An embankment or wall of sandbags, earth, etc., constructed to restrain material from being transported away. A facing of stone, cement, sandbags, etc.
Review of Operation and Maintenance (RO&M) A periodic evaluation of operation and maintenance activities at a particular facility.
Rewind Act of putting new copper insulated wire in the armature windings of a generator. Replacement of an armature (stator) winding of a synchronous generator.
Rex Block A blocking pattern where there is an upper level high located directly north of a closed low.
RF Abbreviation for replicative form.
RFC River Forecast Center. Centers that serve groups of Weather Service Forecast offices and Weather Forecast offices, in providing hydrologic guidance and is…
RFD Razorfen Downs
RFLP See Restriction\-fragment\-length polymorphism.
RGD Ragged
RGN Region
RH Abbreviation for recombinant human.
RHI Range-Height Indicator
rhizobacterium A micro-organism whose natural habitat is near, on, or in, plant roots.
Rhizobia Bacteria in a symbiotic relationship with leguminous plants that results in nitrogen fixation. See Nitrogen fixation.
Rhizobium (pl.: Rhizobia) Prokaryotic species which are able to establish a symbiotic relationship with leguminous plants, as a result of which elemental nitrogen…
Rhizosphere The soils region on and around plant roots.
Rhyolite Volcanic rock (or lava), characteristically light in color and containing 69% silica or more and generally rich in potassium and sodium (felsic…
Rhyolitic domes See also Dome, volcanic; Rhyolite
Ri plasmid A class of large conjugative plasmid s found in the soil bacterium Agrobacterium rhizogenes , which can infect certain plants and cause hairy root disease.
RIA Abbreviation for radioimmunoassay.
Ribbon (Photovoltaic) Cells A type of solar photovoltaic device made in a continuous process of pulling material from a molten bath of photovoltaic material, such as silicon, to form…
Ribbon Lightning Appears to be a broad stream of fire. A succession of strokes, each blown a bit to the side of the previous strokes by wind, but striking so fast that all…
ribonuclease (Abbreviation: RNA se). Any enzyme that catalyses the hydrolysis of RNA.
ribonucleic acid (RY-boh-noo-KLAY-ik A-sid) One of the two types of nucleic acids found in all cells.
Ribonucleic acid (RNA) A chemical similar to a single strand of DNA. In RNA, the letter U, which stands for uracil, is substituted for T in the genetic code.
ribonucleoside See: nucleoside.
Ribonucleotide See: nucleotide.
Ribose A monosaccharide found in all ribonucleosides, ribonucleotides and RNA. Its close analogue, 2-deoxyribose, is similarly found in all deoxyribonucleosides…
ribosomal binding site A sequence of nucleotides near the 5' end of a bacterial mRNA molecule that facilitates the binding of the mRNA to the small ribosomal sub-unit.
ribosomal DNA The coding locus for ribosomal RNA. This is generally a large and complex locus, typically composed of a large number of repeat units, separated from one…
ribosomal RNA (Abbreviation: rRNA). The RNA molecules that are essential structural and functional components of ribosomes, where protein synthesis occurs.
Ribosomal RNA (rRNA) The RNA component of the ribosome. (See RNA.)
Ribosome Cellular organelle that is the site of protein synthesis during translation. See Organelle, Translation.
Ribosome-binding site The region of an mRNA molecule that binds the ribosome to initiate translation.
ribosome-inactivating protein (Abbreviation: RIP). A class of plant proteins that inhibit normal ribosome function, and are thus highly toxic.
Ribosomes Small cellular components composed of specialized ribosomal RNA and protein; site of protein synthesis. See also: RNA
Ribozyme See Catalytic RNA.
ribulose A keto-pentose sugar (C5H11O5) involved in the carbon dioxide fixation pathway of photosynthesis.
ribulose biphosphate (Abbreviation: RuBP). A five-carbon sugar combined with carbon dioxide to form a six-carbon intermediate in the first stage of the dark reaction of…
Richter Magnitude Scale Developed in 1935 by Charles Richter to measure and compare the size of earthquakes.
Richter scale A scale of numerical values, proposed by C. F. Richter, to describe the magnitude of an earthquake, ranging from 1 to 9, by measurements made in…
Ridge A line or wall of broken ice forced up by pressure. May be fresh or weathered.
Ridge Ice Ice piled haphazardly one piece over another in the form of ridges or walls.
Riffle A stretch of choppy water caused by an underlying rock shoal or sandbar. A run is a long riffle.
Riffle and pool complex A water habitat composed of riffles (characterized by water flowing rapidly over a coarse substrate) and pools (deeper areas of water associated with…
Rift An area where the Earth's crust and lithosphere is being pulled apart by extensional tectonic forces.
Rift zone A tectonic feature characterized by a central linear downfaulted segment (graben) with parallel normal faulting and flanking uplifts (horsts).
Right Abutment See abutment.
Right Ascension The celestial longitude of the sun. This value is 0 at the vernal equinox, 90 at the summer solstice, 180 at the autumnal equinox and 270 at the winter…
Right Entrance Region Used interchangably with Right Rear Quadrant; the area upstream from and to the right of an upper-level jet max (as would be viewed looking along the…
Right Mover A thunderstorm that moves appreciably to the right relative to the main steering winds and to other nearby thunderstorms.
Right of way The right of a party to pass over the land of another.
Right Rear Quadrant (Abbrev. RRQ) - Used interchangably with Right Entrance Region; the area upstream from and to the right of an upper-level jet max (as would be viewed…
Right-lateral fault See Fault, right-lateral
Right-of-way (ROW) The legal right to cross the lands of another. Also used to indicate the strip of land for a road, railroad, or power line.
Right. A temporary privilege granted to existing common shareholders to purchase additional shares directly from the company at a stated price.
Rigid Insulation Board An insulation product made of a fibrous material or plastic foams, pressed or extruded into board-like forms.
Rigid pipe Pipe designed to transmit the backfill load to the foundation beneath the pipe. Rigid pipe must be supported on the bottom portion of the pipe.
Rill A small and shallow incision into topsoil layers resulting from erosion by overland flow or surface runoff that is common on slopes of unvegetated ground…
Rime Rime A white or milky and opaque granular deposit of ice formed by the rapid freezing of super-cooled water drops as they impinge upon an exposed object.
Rime Ice An opaque coating of tiny, white, granular ice particles caused by the rapid freezing of supercooled water droplets on impact with an object.
rinderpest Cattle plague; a viral infection of cattle, sheep and goats.
Ring gate A ring- or annular-shaped steel drum operating in a recess or gate chamber in a spillway crest and controlled in a manner similar to a drum gate. See gate.