Month: August 2020
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Halophile
Microorganisms that require NaCl (salt) for growth (they are called obligate halophiles). Those that do not require it, but can grow in the presence of high NaCl concentrations, are called facultative halophiles. Natural habitats containing high salt concentrations are, for example, the Great Salt Lake in Utah, the Dead Sea in Israel and the Caspian…
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Hairpin loop
A section of highly curving, single-stranded DNA or RNA formed when a long piece (string) of the DNA or RNA bends back on itself and hydrogen-bonds (is able to base pair) in some regions to form double-stranded regions. The structure can be visualized by taking a human hair, bending it back on itself and holding…
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H.pylori
A bacteria that has been linked (e.g., cause) to gastric ulcers and other gastric problems in humans. That link was first announced by Barry Marshall in the early 1990’s.
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Gut-associated lymphoid tissues (GALT)
A variety of specialized lymph-reticular tissues that line the inside of an animal’s digestive system. GALT include Peyer’s Patches, the appendix, and small solitary lymphoid tissues in the gut. They constitute the intestinal immune system (response to antigens). A term used for all lymphoid tissue associated with the gastrointestinal tract, including the tonsils, appendix, and…
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Guanosine triphosphatases
These are G-proteins (enzymes) which are crucial for growth, movement, and maintenance of the cell’s shape. When active, GTPases are bound to cell membranes (surfaces) by an isoprene molecule (receptor).
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Growth hormone-releasing factor (GRF or GHRF)
Also termed growth hormone-releasing hormone (GRH). A factor that causes the release of growth hormone. It is 44 amino acids in length.
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Growth curve
The change in the number of cells in a growing culture as a function of time. A graph of heights and weights, head circumference, and body mass index of infants and children of various ages. A line connecting the data points produces the curve. Usually the changes in height and weight are shown on the…
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GRAS List
A list of food additives/ingredients considered to be Generally Recognized as Safe, by the American Government’s Food and Drug Administration (FDA). This list of additives is judged to be safe by a panel of FDA pharmacologists and toxicologists, who base their judgment upon data that is available for each ingredient. In practice, those additives for…
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Granulocidin
A protein produced by white blood cells, which has demonstrated (in the laboratory) an ability to kill a broad spectrum of pathogens.
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Gram-positive (G+)
Pertaining to bacteria, holding the color of the primary stain (blue) when treated with Gram’s stain (a commercial staining agent), or Gentian violet solution. In contrast to the gram-negative bacteria, the gram-positive bacteria possess a much thicker peptidoglycan cell wall (capsule). Because of this, the blue crystal violet dye (with which the bacteria were stained)…