Chapter 5


Eukaryotic Microorganisms



Eukaryotic cells (Eukaryotes)

  More complex than prokaryotes

  Possess a true nucleus and membrane-bound organelles

  May be single-celled or multicellular

  May or may not have cell walls

  Include members of Domain Eukarya




  Saprobic organisms - live off of dead organic matter

  Live mostly on land and are nonmotile

  Have rigid cell walls made of chitin

  Diverse group ranging from single-celled yeasts to multicellular molds & mushrooms

  Colonies of filamentous molds have hairlike texture due to hyphae

  Asexual Reproduction - budding, fragmentation, or spore formation

  sporangiospores and conidiospores

  Sexual Reproduction - spore formation



Fungi in Medicine and Industry

  Many cause food spoilage and disease in plants

  Used to produce antibiotics, alcohol, and vitamins

  Saccharomyces bakers yeast used to make bread, beer, and wine

  Penicillium - produces penicillin

  Mycoses - Fungi that grow in or on the human body and cause a disease

  Immunocompromised individuals are the most vulnerable

  cause skin infections, lung infections, allergies or produce toxins

  Aspergillis liver and thyroid cancer

  Candida oral and skin infections




  Plant-like organisms that contain chlorophyll and a cell wall of cellulose

  Divided into groups based on photosynthetic pigments

  One of the primary producers of carbohydrates and oxygen

  Found near the surface of salt or fresh water

  Can be microscopic or macroscopic, unicellular or multicellular

  Reproduce by binary fission, fragmentation, or sexual reproduction

  Can cause skin infections and red tides

  toxins induce paralytic shellfish  




  Diverse group of single-celled eukaryotes, larger than prokaryotes

  Found on land and in water

  Lack rigid cell walls

  Reproduce by binary fission and sexual reproduction

  Exist in active trophozoite or dormant cyst forms

  Classification is based on type of locomotion



Classification of Protozoans

  Flagellated Protozoa





  Amoeboid Protozoa




  Ciliated Protozoa


  Nonmotile Protozoa







Parasitic Helminths

  Multicellular parasites that enter the body through contaminated food, insect bites, or direct skin penetration

  Most are not microscopic but they are included among microorganisms because of their importance in human diseases

  Diagnosis often requires microscopic examination of eggs and larvae in feces and tissue



Chapter 22



Parasitic Helminth Diseases



Nematodes (roundworms)

  Have elongated, cylindrical bodies

  Inhabit the gastrointestinal tract and produce symptoms of intestinal distress

  Some may enter heart, lungs, throat, or other tissues                             

  Trichuris trichiura whipworm

  Human to human transmission by ingesting eggs from soil contaminated with human feces

  Causes bowel hemorrhage, dysentery, and rectal prolapse

  Enterobius vermicularis pinworm

  Human to human transmission by ingesting eggs from contaminated food, drink, fingers

  Causes anal itching, nausea, abdominal discomfort, and diarrhea

  Ascaris lumbricoides ascariasis

  Human to human transmission by ingestion of contaminated food, drink, or objects placed in the mouth

  Can invade the liver and gall bladder and  cause allergic reactions

  Worms may emerge from the nose and mouth

  Necator americanus hookworm

  Has cutting teeth on the mouth that anchor it to the intestinal villi

  Burrows into the skin from soil contaminated with human feces 

  Causes nausea, vomiting, cramps, diarrhea, and anemia

  Trichinella sp.- trichinosis

  Acquired from eating undercooked pork containing cysts

  Causes muscle and joint pain and can involve the heart and brain



Cestodes (tapeworms)

  Have long flat, ribbon-like bodies and hooklets and suckers that attach to the intestine

  Infections often go unnoticed, but may cause mild abdominal discomfort or anemia

   Can be serious if tapeworm obstructs the GI tract

  Taenia solium pork tapeworm

  Acquired from eating undercooked pork

  Diphyllobothrium latum fish tapeworm

  Acquired from eating undercooked fish



Trematodes (flukes)

  Have flat, ovoid bodies and suckers that hold organism in place and suck fluids from the host

  Life cycle usually involves the liver and may cause liver malfunction

  Clonorchis sinensis Chinese liver fluke

  Acquired from eating undercooked freshwater fish

  Causes thickening of bile duct and granuloma formation in the liver

  Fasciola hepatica Sheep liver fluke

  Acquired from eating wild watercress

  Causes vomiting, diarrhea, liver swelling, and bile obstruction

  Schistosoma mansoni blood fluke

  Burrows into the skin from water contaminated with human feces

  Causes liver swelling or malfunction