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major classes of microorganisms

viruses, rickettsiae, fungi, protozoa, bacteria

one organism receives benefit from another organism, but causes it no harm


one organism derives benefit from another organism, at the other's expense


one organism produces substances or causes conditions which are lethal for other organisms


two different kinds of organisms living independently without affecting the other


characteristics of protozoa

are multicellular, are microscopic, take their food in solid particles, are nonmotile, reproduce sexually or asexually by fission, when subjected to adverse conditions, the become very active.

transmitted by the bite of a female anopheles mosquito or by a contaminated hypodermic needle or blood transfusion


caused by entamoeba histolytica

amebic dysentery

characterized in women by vaginitis with a profuse, cream colored, foulsmelling discharge

trichomonas infection

characterized by chills and fever


occurs following fecal contamination of food or drink

amebic dysentery

symptoms are intense diarrhea with bloody, mucous filled stools

amebic dysentery

caused by a parasite of the plasmodium genus (several species)


characteristics of fungi

include yeasts and molds, are in plant kingdom, lack chlorophyll, contain over 100,000 species, some are a common sight on stale bread, rotten fruit, or damp leather, exist as parasites or saprophytes, most medically important fungi are visible to the naked eye.

characteristics or yeasts

reproduce by budding, some are used commercially in preparing beer, sine, and breads, are unicellular, microscopic organisms, a common cycosis of this is caused by candida albicans

characteristics of mold

are characterized by a fuzzy growth of interlacing filaments called hyphae, reproduce by spores, some may be seen on foods such as bread and cheese, are multicellular, a common mycosis if this is caused by tinea capitis

characteristics of bacteria

unicellular, simple plant organisms, ordinarily do not contain chlorophyll, have approximately 2000 known species and are found only on food, only about 100 species produce disease in human beings, are classified as pathogenic or nonpathogenic, reproduce asexually binary fission, have no cell wall


short, slightly bent, comma shaped rod


rod or cylinder shapes that appear in chains


sphere or round forms that appear in pairs


rod or cylinder shapes that appear in pairs


longer, rigid, curved organism, usually with several spirals and several flagella


sphere or round forms that arrange themselves in grapelike clusters


are hair like processes that cause the bacteria to move along in liquid by their wavelike rhythmic contractions


are round structures of condensed protoplasm that are formed within the bacteria


are layers that surround many bacterial cells and interfere with phagocytosis by white blood cells


are liberated only when the bacterial cell dies and disintegrates, examples are organisms which cause typhoid fever and bacillary dysentery.


diffuse out of the intact bacterial cells into the surrounding medium or tissue, examples are organisms causing tetanus, gas gangrene, diphtheria, and scarlet fever, are the most potent toxins known.

growth requirements of bacteria

favors growth, autotrophic bacteria use carbon dioxide and other inorganic compounds for food and are nonpathogenic, heterotrophic bacteria require living or dead organic matter for food and are pathogenic, parasites utilize living organic matter for food, saprophytes utilize dead organic matter for food, high heat destroys most bacteria, most bacteria killed in direct sunlight

characteristics of helminths

multicellular, are animal parasites, are commonly called worms.

types of hepatitis

chemically induced hepatitis could be caused by alcohol.

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