- Gamma globulin
- Consists of serum proteins with antibody activity.
- Ganglion
- A group of nerve cells located outside the central nervous system.
- Gangrene
- Tissue death caused by lack of blood flow. Most often, it is caused by such certain bacterial infections as Clostridium perfringens, which produces gas gangrene that release gas into the dying tissues by bacterial metabolism.
- Gardnerella
- An emerging pathogen (Gardnerella vaginalis) much like Mobiluncus, Plesiomonas, and Aeromonas, producing vaginitis instead of diarrhea. It is a Gram-negative, relatively inert bacillus and part of the normal vaginal flora of about 10% of the female population. However, in those who develop vaginitis, the percentage rate rises to about 40%.
- Gas gangrene
- A type of tissue infection typically produced from the bacteria Clostridium perfringens (type A), C. septicum, or C. novyi. Infection causes the tissues to swell and contain pockets of gas formed by bacterial metabolism, reulting in the necrosis or death of the infected tissue, leaving surgery the only recourse. Infection is transmitted via open wounds or sores.
- Gastroenteritis
- An infection of the intestinal tract, often accompanied by diarrhea.
- Gene
- A linear sequence of DNA nucleotides that form a functional unit of a chromosome.
- Generalized transduction
- A type of transduction in which a fragment of DNA from a degraded chromosome of an infected bacterial cell is accidentally incorporated into a new phage particle during replication and, thereby, is transferred to another bacterial cell.
- Generation time
- The time it takes for an organism to produce one new generation of progeny.
- Genetic drift (of influenza virus)
- The accumulation of point mutations which subtly alter the antigenic structure of the virus.
- Genetic shift (of influenza virus)
- The reassortment of virus RNA molecules within a virus particle, resulting from double infection of a single cell. Genetic shift is a rare event and results in major antigenic changes in the virus.
- Genome
- The complete set of genes present in an organism; the nuclear content of a virion.
- Genotype
- The precise genetic constitution of an organism (compare phenotype).
- Genus
- A group of closely related species that rank below the family; a taxon consisting of one or more species; the first name of an organism on binomial nomenclature, e.g., Escherichia in Escherichia coli.
- Geosmin
- A secondary metabolic product of streptomycete bacteria that gives soil its characteristic smell, especially apparent immediately after digging.
- Germ tube
- Pseudomycelium produced by cells of Candida albicans when incubated in serum at 37°C (98.6°) for two hours.
- Germacide
- A chemical agent that destroys germs, but not all organisms.
- Germs
- Pathogenic microorganisms, and a term also used to refer to any microorganism capable of producing an infection.
- Giardia lamblia
- A protozoan causing the disease Giardiasis (also known as ‘beaver fever’). In Europe, the organism is sometimes called Lamblia intestinalis. Giardia lamblia attaches itself to the intestines, where they easily multiply, causing gas. It is one of the most familiar intestinal infections causing weeks of cramps, diarrhea, and considerable weight loss. Divers often develop protozoan infections, especially giardiasis and Entamoeba histolytica because they are often found in all types of waterways, including drinking water.
- Gingivitis
- The most common form of peridontal disease (a disease involving the tissues surrounding the teeth).
- Glioma
- A type of malignant brain tumor.
- Glomerulonephritis
- A potentially fatal streptococcal inflammation of the glomeruli in the kidney.
- Glucagon
- A pancreatic hormone that increases blood glucose levels.
- Glucocorticoid
- An adrenal cortex hormone that affects salt and water metabolism and stimulates conversion of noncarbohydrates into carbohydrates.
- Glycocalyx
- The glycoprotein-polysaccharide covering that surrounds many cells.
- Gnathostoma spinigerum
- The parasitic roundworm whose larva causes gnathostomiasis, a disease is transmitted by eating undercooked fish or snake. It affects the brain, the eye, the liver, and subcutaneous tissues.
- Gonococcus
- Another name for Neisseria gonorrhoeae, the Gram-negative diplococcus bacterium that causes the disease gonorrhea.
- Gonorrhea
- A sexually transmitted disease produced from the bacterium Neisseria gonorrhoeae.
- Gram-negative
- A term used to describe bacteria that turn pink when stained with Gram’s stain.
- Gram-positive
- A term used to describe bacteria that turn blue when stained with Gram’s stain.
- Gram’s stain
- A method of staining devised by Dr. Christian Gram that is used to differentiate between various types of bacteria.
- Granulation tissue
- Small raised lumps of tissue that form during the healing of wounds.
- Granulocyte
- One type of white blood cell that contains granules in the cytoplasm; a polymorphonuclear leukocyte.
- Granulomas
- Tumor-like masses or nodules of scar tissue resulting from an inflammatory reaction.
- Ground itch
- Itchy patches of skin, pimples, and/or blisters, resulting from infection of hookworm larvae.
- Group A strep
- (see Streptococcus pyogenes).
- Growth rate
- The number of generations produced by an organism in sixty minutes.
- Gumma
- Ulcerated lesions, called granulomatous inflammations, that destroy tissues associated with tertiary syphilis.
