G
1-10 A B C D E F G H I J K L M N O P Q R S T U V W XYZG-band-Giemsa chromosome banding
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G-band-Giemsa chromosome banding is a unique chromosome staining technique used in human cytogenetics to identify individual chromosomes, which produces characteristic bands.
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GABA (gamma-aminobutyric acid) is an acid found in the central nervous system -- predominantly in the brain -- where it acts as an inhibitor of nerve impulses.
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A galleyis the kitchen of a ship or aircraft.
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A galvanometer is an instrument used to measure the intensity of an electric current, usually by the deflection of a magnetic needle.
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Gamma radiation is electromagnetic radiation of shorter wavelength and higher energy than X-rays. Gamma rays have greater penetration than X-rays and are harmful to living tissues. Carefully controlled doses are used in radiotherapy.
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A gamma ray is a photon emitted spontaneously by a radioactive substance.
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Ganglia are any structures containing a collection of nerve cell bodies.
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A ganglion is any structure containing a collection of nerve cell bodies in the central or peripheral nervous system.
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Gas chromatography is the process of separation and analysis of different substances according to their different attraction to a standard absorbent substance.
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Gas exchange is the exchange of carbon dioxide for oxygen.
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The gas exchange ratio (respiratory exchange ratio, R) is the ratio of carbon dioxide output to oxygen intake. The value changes under different metabolic conditions, but the average value is considered to be 0.825.
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Gastric acid is the liquid secreted by the gastric glands of the stomach; its main digestive constituents are hydrochloric acid, mucin, renin and pepsinogen. The acid acts to aid in digesting food and killing unwanted bacteria and organisms that have been ingested with food.
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The gastrocnemius is a muscle that forms the greater part of the calf of the leg; it flexes the knee and foot so that the toes point downward.
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The gastrocnemius medialis is the section of the gastrocnemius muscle that forms the greater part of the calf of the leg.
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Gastroenteritis is the inflammation of the mucous membranes that line the stomach and intestine.
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Gastrointestinal refers to the stomach and intestines.
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Gastrointestional physiology is the study of the function of the stomach and intestines.
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The Gauer-Henry reflex can be described as follows: the headward shift of fluids seen in space flight is thought to produce a transient increase in central blood volume; the transient increase is detected by stretch receptors in the heart and interpreted as an increase in total blood volume. A compensatory loss of water and sodium is then thought to be effected by a series of neural, humoral and direct hydraulic mechanisms.
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Gel electrophoresis is the process of separating a mixture of molecules in a gel media by the application of an electric field. In general, molecules with similar electric charges and density will migrate at the same rate together in the gel.
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The Gas Exchange Measurement System,or GEMS, is a unit consisting of two Gas Analyzer Systems that measures the CO2 and H2O vapor going into and leaving the leaf chamber.
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The gene is the functional unit of heredity which occupies a specific place on a chromosome.
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Gene expression refers to the transcription and translation of a specific part of the DNA code with the ultimate outcome being protein synthesis.
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Gene regulation is the control of gene transcription by chemical factors that regulate the RNA polymerase binding to DNA.
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Genetic refers to genetics, which is a branch of science concerned with heredity.
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The genetic program, also called the genetic code, is the information carried by the genes (DNA and RNA) and determines how an organism develops, including its appearance, function, and instincts.
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Geomagnetic means pertaining to the magnetic field observed in and around the Earth.
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Geosynchronous refers to a special type of orbit around the Earth, where an object orbits the Earth in the same direction and at the same speed as the Earth's own rotation. This results in the orbiting object remaining in a fixed position above a geographic point on the surface of the Earth. Telecommunications satellites are often put into geosynchronous orbit so that they may be accessible via radio waves from one area of Earth at all times.
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German Aerospace Research Establishment (DFVLR) is responsible for basic research in the German space program, as well as management, operations and general support of all German sponsored space activities. DFVLR was renamed DLR in 1989. The agency is headquartered in Cologne, with other centers in Berlin, Göttingen Braunschweig, Stuttgart, Oberpfaffenhofen (Munich).
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Germination is the process of beginning to grow or develop.
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Giddy means having a reeling, lightheaded sensation; dizzy.
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Giemsa staining is a unique chromosome staining technique used to identify individual chromosomes, in which characteristic bands are produced. It is also known as G-banding.
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Girth is the distance around something; circumference.
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Glia refers to glial cells or neuroglia, the special connective tissue of the central nervous system.
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Glial refers to glia or neuroglia, the special connective tissue of the central nervous system.
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The globus pallidus is a structure in the brain involved in the regulation of voluntary movements at a subconscious level.
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The glomerular filtration rate (GFR) is the amount of glomerular filtrate -- a substance which is the same as plasma except that it has no significant amount of proteins -- that is formed each minute in all nephrons of both kidneys. The GFR is normally about 125 ml/minute.
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A glovebox is a device used to isolate an area for work with potentially hazardous substances or materials which need to be free from direct contact with the outside environment for any reason. Most gloveboxes used in flight are small, tightly enclosed boxes having a glass panel for viewing inside and special airtight gloves which a person on the outside can use to manipulate objects inside.
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A glucocorticoid is a steroid hormone that predominantly affects the metabolism of carbohydrates and, to a lesser extent, fats and proteins (and has other effects). Glucocorticoids are made in the outside portion (the cortex) of the adrenal gland. Cortisol is the major natural glucocorticoid. The term glucocorticoid also applies to equivalent hormones synthesized in the laboratory.
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Glucose is a simple sugar found in certain foods, especially fruit, and is a major source of energy occurring in human and animal body fluids. The determination of blood glucose levels is an important diagnostic test in diabetes and other disorders.
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Glucose-6 phosphate dehydrogenase is an enzyme which participates in the formation of glucose from carbon dioxide as part of the process of photosynthesis.
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Glutamate is a derivative of glutamic acid, an amino acid occurring in proteins.
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Glutaminase is an enzyme found in the kidney that catalyzes the breakdown of the amino acid glutamine to ammonia and glutamic acid. This breakdown is a stage in the production of urea, a major component of urine.
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Glutaraldehyde is a compound used as a fixative for localization of enzyme activity; tissues fixed in glutaraldehyde may be stored for weeks or months before processing.
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Glyceraldehyde phosphate dehydrogenase is an enzyme found in cells that participates in the glucose metabolism by removing a hydrogen atom from glyceraldehyde phosphate, a glucose metabolite, and adding a phosphate group to form 1,3 bisphosphoglycerate.
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Glycine is an amino acid constituent of proteins in the human body.
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Glycogen is a large, complex carbohydrate molecule produced from glucose in the liver and muscles when blood sugar levels are high. Glycogen is broken down into lactic acid when it is used as an energy source in the liver or muscles.
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Glycolysis is the process of transforming glucose into lactic acid in the muscles (or other tissues), for energy production when sufficient oxygen is not available in an emergency situation.
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Glycolytic enzymes are a part of the glycolytic pathway that act as a catalyst. They work in sequence to convert glucose to pyruvate which produces adenosine triphosphate (ATP), the energy carrier.
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Glycoside is any of several carbohydrates that yield a sugar and a non-sugar on hydrolysis. The plant digitalis purpurea yields a glycoside used in the treatment of heart disease.
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A GN2 freezer is a small storage canister which uses gaseous nitrogen to keep samples at or below freezing.
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The Golgi apparatus is a collection of vesicles and folded membranes in a cell, usually connected to the endoplasmic reticulum. It stores and later transports the proteins manufactured in the endoplasmic reticulum. Golgi cells are types of neurons (nerve cells) within the central nervous system.
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The Grab Air Sampler is a device which used to collect air samples. The device is evacuated thus causing air to be quickly sucked into the device once the valve is opened.
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The Grab Sample Container (GSC) is a device which is used to collect air samples. The device is evacuated thus causing air to be quickly sucked into the device once the valve is opened.
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Gram-negative denotes a bacteria that stains pink when stained with Gram's stain. This staining technique is useful in bacterial taxonomy and identification and to indicate fundamental differences in cell wall structure.
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Gram-positive denotes a bacteria that stains purple-black when stained with Gram's stain. This staining technique is useful in bacterial taxonomy and identification, and to indicate fundamental differences in cell wall structure.
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Gram's stain is a method to differentially stain bacteria. Bacterial smears are fixed by flaming, stained in a solution of crystal violet, treated with iodine solution, rinsed, decolorized and then counterstained with safranin. Microorganisms are classified as either Gram-positive or Gram-negative.
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Granulocytosis is an increase in the total number of granulocytes, a type of leukocyte, in the blood.
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Graviperception is the sense that gives knowledge of body position, equilibrium, direction of gravitational forces, and the sensation of "down" or "up." This perception in humans is provided by highly specialized receptor organs and nerve endings in the inner ear, joints, tendons and muscles, that give the brain information about body position. Other organisms, like plants, also possess graviperception.
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Gravireceptors are highly specialized receptor organs and nerve endings in the inner ear, joints, tendons and muscles, that give the brain information about body position, equilibrium, direction of gravitational forces, and the sensation of "down" or "up."
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Gravisensitivity is the sense of body position, equilibrium, direction of gravitational forces, and the sensation of "down" or "up." This sense in humans is provided by highly specialized receptor organs and nerve endings in the inner ear, joints, tendons and muscles, that give the brain information about body position. Other organisms, like plants, also possess gravisensitivity.
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The gravitational field of the Earth is what pulls everything towards the center of our planet. Its force is defined as 1g (one "g" or one gravity). In comparison, the gravitational force present on the moon is 0.6 g's, this weaker force allowed the astronauts to do their famous moon-jumps.
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Gravitational loading refers to the application of force to a bone or part of the body. Under normal circumstances on Earth, gravity "loads" the bones and muscles with the force required to support the body.
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A model of gravity perception in plants whereby plant cells perceive gravity as the protoplast is displaced within the cell wall, exerting tension between the plasma membrane and the cell wall on the top and compression on the bottom.
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A gravitoinertial environment is an environment in which gravity and inertia exist.
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The axis of reference of any plant organ with respect to the gravity vector. Roots growing down have a GSA of 0o. Shoots growing up, a GSA of 180o with all range of possibilities in between to account for the shoots of hanging or creeping plants and lateral roots for example.
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A gravity gradient is a change in the gravitational force depending on the relative position to the Earth.
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Gravity receptors, also known as gravireceptors, are highly specialized receptor organs and nerve endings in the inner ear, joints, tendons and muscles, that give the brain information about body position, equilibrium, direction of gravitational forces, and the sensation of "down" or "up."
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Growth Hormone (GH), also called somatotropin, is a protein hormone of the anterior lobe of the pituitary. It is produced by the acidophil cells and it promotes body growth, fat mobilization, and inhibition of glucose utilization. It is diabetogenic when present in excess.
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A growth medium contains nutrients and is a substance on or in which microorganisms or cells can be grown.
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Guanylyl cyclase is an enzyme that catalyzes the synthesis of cyclic guanosine 3',5'-monophosphate (cGMP), a cyclic nucleotide that participates in intracellular signaling, from the substrate guanosine 5-triphosphate (GTP). There are two major classes of this enzyme, a soluble form and a transmembrane form. The catalytic activity of the soluble form is activated by the free radical nitric oxide (NO) when it complexes with the heme cofactor of the enzyme.
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A reporter gene whereby gene expression is visualized by a histochemical stain resulting in a blue color in the tissue.
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Gut wall refers to the wall of the intestine. It is here that most of the absorption of food from the digestive track into the body takes place.