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Chapter 17 Outline

Chapter 17 Outline - Chapter 17 Eukaryotic Microorganisms...

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Chapter 17 Eukaryotic Microorganisms: The Parasites Introduction 17.1 Classification and Characteristics of Protists The Protists Are a Perplexing Group of Microorganisms Most are unicellular Many are free-living, thriving in environments with water Green algae have chloroplasts and perform photosynthesis Some dinoflagellates cause red tides Radiolarians have silica plates that form deposits on the ocean floor Foraminiferans have chalky, snail-shaped skeletons Protozoans include many motile, predatory, and parasitic protists The Protozoa Encompass a Variety of Lifestyles Some parabasalids live mutualistically in termite guts Diplomonads, including Giardia intestinatlis , have bilateral symmetry Kinetoplastids include trypanosomes causing sleeping sickness and Leishmania Amoebozoans are mostly free-living Amoeboid motion occurs by the formation of pseudopods Pseudopods also form food vacuoles for ingestion Ciliates are covered with rows of hair-like cilia The pellicle provides cell structure and stores calcium ions Contractile vacuoles eliminate excess water Ciliates have two types of nuclei: macronuclei and micronuclei Apicomplexans include parasites such as Plasmodium and Toxoplasmosis Parasite Life Cycles Have Some Unique Features The infective form of some protozoa is a trophozoite, others a cyst The sexual cycle occurs in the definitive host The asexual cycle occurs in the intermediate host 17.2 Protozoal Diseases of the Skin, and the Digestive and Urinary Tracts Leishmania Can Cause a Cutaneous or Visceral Infection Several species cause leishmaniasis It is transmitted by sandflies of the genus Phlebotomus L. major causes cuteaneous disease with ulcerative sores L. donovani causes a visceral disease (kala azar) affecting white blood cells, spleen, and liver Several Protozoal Parasites Cause Diseases of the Digestive System Amoebiasis is the second leading cause of death from parasitic disease It is caused by Entameoba histolytica Cysts enter the body through food or water contaminated with feces Trophozoites emerge in the intestines, causing loose stools and stomach cramping and pain Lesions may form, causing pain, bloody stools and fever (amoebic dysentery) Rarely, parasites can spread to other organs and cause fatal abcesses Giardiasis is caused by Giardia intestinalis Transmission occurs through food or water contaminated with sewage containing cysts
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