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Prokaryotes, Viruses, and Protistans

Prokaryotes, Viruses, and Protistans. Microorganisms. Single-celled organisms that are too small to be seen without a microscope Bacteria are the smallest living organisms Viruses are smaller but are not alive. The Prokaryotes. Only two groups Archaebacteria and Eubacteria

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Prokaryotes, Viruses, and Protistans

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  1. Prokaryotes, Viruses, and Protistans

  2. Microorganisms • Single-celled organisms that are too small to be seen without a microscope • Bacteria are the smallest living organisms • Viruses are smaller but are not alive

  3. The Prokaryotes • Only two groups • Archaebacteria and Eubacteria • Arose before the eukaryotes

  4. Prokaryotic Characteristics • No membrane-bound nucleus • Single chromosome • Cell wall in most species • Prokaryotic fission • Metabolic diversity

  5. Prokaryotic Body Plan pilus DNA bacterial flagellum ribosomes in cytoplasm plasma membrane capsule cell wall

  6. Bacterial Shapes coccus bacillus spirillum

  7. Archaebacteria Methanogens Extreme halophiles Extreme thermophiles

  8. Archaebacteria Habitats

  9. Eubacteria • Includes most familiar bacteria • Have fatty acids in plasma membrane • Most have cell wall; always includes peptidoglycan • Classification based largely on metabolism

  10. Metabolic Diversity • Photoautotrophs • Chemoautotrophs • Chemoheterotrophs

  11. Bacterial Genes • Bacteria have a single chromosome • Circular molecule of DNA • Many bacteria also have plasmids • Self-replicating circle of DNA that has a few genes • Can be passed from one cell to another

  12. Prokaryotic Fission

  13. Video: E. coli Reproduction • http://www.college.ucla.edu/webproject/micro7/lecturenotes/finished/ecolivideo.mov

  14. nicked plasmid in donor cell conjugation tube to recipient cell Conjugation

  15. The Normal Flora • The normal flora of humans is exceedingly complex and consists of more than 200 species of bacteria. • The mixture of organisms regularly found at any anatomical site is referred to as the normal flora.

  16. A Friendly Bacteria: E. coli • Commonly inhabits the intestines of vertebrates • E. coli does not normally infect us • Many benefits: vitamin K and the B complex are produced by E. coli • prevent colonization by pathogens • stimulate the production of cross-reactive antibodies

  17. E. coli strain O157:H7.A Dangerous Form • This mutant can be transmitted in food or water • Think “White Water” and the “Jack in the Box” hamburger incidents • Both made national news when many people became ill and some died.

  18. Sewage Pollution Indicator • E. coli in streams, drinking water and surface waters of all kinds may indicate a problem with sewage and or farm runoff. • Testing for unusual levels of these organisms is routinely done by public health officials • Parks, swimming pools, restaurants etc may be closed if E. coli is detected

  19. E. coli Photos Culture plate EM cells http://www.bact.wisc.edu/bact330/nfE.coli_colonies.jpeg

  20. Park settles last E. coli suit Patricia Guthrie - StaffFriday, December 15, 2000 The last of a dozen lawsuits, filed by families of children sickened in a 1998 E. coli outbreak tied to Cobb County's White Water park, has been settled out of court for an undisclosed sum, attorneys said Thursday. The family of Jordan Faith Shook of Cartersville, whose symptoms were among the most severe of the 26 children sickened by E. coli O157:H7, agreed to an out-of-court settlement. The settlement was sealed in court records and will not be disclosed, said Bill Marler, attorney for James and Judy Shook, Jordan's parents…… http://www.marlerclark.com/news/whitewater10.htm

  21. Necrotizing fasciitis: "The flesh-eating bacteria" Streptococcus pyogenes strains (as well as others) rarely cause “necrotizing fasciitis” These infections are extremely serious Sometimes necessitate amputation or result in severe disfigurement.

  22. Photomicrograph of Streptococcus pyogenes http://www.cellsalive.net/photos/images/strep1.jpg

  23. Unexpected Consequences • One weekend in June of 1998 while Cassie Moore was camping with her three children, she obtained a minor cut on her finger, which she bandaged properly. She also injured the left side of her body participating in sports. Not thinking much of either, she bandaged the cut, and went to bed (Moore, 1999). http://www.bact.wisc.edu:81/ScienceEd/stories/storyReader$89

  24. Warning! • The next two slides are very graphic. They show the results of necrotizing fasciitis!! • You don’t have to look at them if you are squeamish!

  25. Severe Case http://www.bact.wisc.edu:81/ScienceEd/stories/storyReader$89

  26. Amputee

  27. EPA finds contaminated drinking water on planes • WASHINGTON (Reuters) -- A surprising number of drinking water systems on domestic and foreign commercial aircraft tested this summer by the government did not meet federal standards because they were contaminated with potentially harmful bacteria, regulators said Monday. (Tuesday, September 21, 2004 Posted: 10:46 AM EDT (1446 GMT) )

  28. Virus • Noncellular infectious agent • Consists of protein wrapped around a nucleic acid core • Cannot reproduce itself; can only be reproduced using a host cell

  29. Viral Body Plans • Genetic material is DNA or RNA • Coat is protein Complex virus (bacteriophage) Helical virus Polyhedral virus

  30. Enveloped Virus (HIV) lipid envelope; proteins span the envelope, line its inner surface, spike out above it viral coat (proteins)

  31. Viral Multiplication - Basic Steps • Virus attaches to host cell • Whole virus or genetic material enters host • Viral DNA or RNA directs host to make viral genetic material and protein • Viral nucleic acids and proteins are assembled • New viral particles are released from cell

  32. Lytic Pathway Lysis Assembly Assembly Virus injects genetic material Production of viral components

  33. Lysogenic Pathway Stimulus may cause cell to enter lytic pathway • Latent period extends the cycle • Viral DNA becomes part of host chromosome for a time Viral material passed on Viral material integrated

  34. Video: Virus Reproduction • http://www.med.sc.edu:85/movies/phageh.mov

  35. Replication of anEnvelopedVirus Transcription of viral genes Translation DNA replication Proteins Assembly

  36. Video: Bioterrorism • http://www.rockefeller.edu/vaf/media.html

  37. Food and Water Borne Viruses • Norwalk and Norwalk-like viruses • Polio • hepatitis A (HA) • Massive virus discovered in water tower

  38. Norwalk and Norwalk-like viruses • small round structured viruses (SRSVs) • strand RNA • single structural protein • viral gastroenteritis • self-limiting, mild, and characterized by nausea, vomiting, diarrhea, and abdominal pain.

  39. http://rhino.bocklabs.wisc.edu/virusworld/jysart/norwalk_asv2001.jpghttp://rhino.bocklabs.wisc.edu/virusworld/jysart/norwalk_asv2001.jpg

  40. Disney ship docks with 195 ill PORT CANAVERAL, Florida (CNN) --Sunny skies greeted the Disney cruise ship Magic as it docked here early Saturday, carrying 195 sick passengers and crew members. Norwalk virus. (2002) http://www.cnn.com/2002/TRAVEL/11/30/disney.sick.cruise/

  41. Massive Virus Discovered in Water Tower “The largest virus ever discovered has been found in a water-cooling tower in Bradford, England. It was lurking inside single-celled organisms called amoebae, but its discoverers believe that it may also be capable of infecting humans. “ http://www.newscientist.com/news/news.jsp?id=ns99993559

  42. Photo from the New Scientist girth of 400 nanometers (visible with a good light microscope) 900 genes

  43. Polio • Small water-food borne RNA virus • In about 1% of the infected population, the virus attacks and kills motor neurons • This results in various degrees of paralysis http://www.rednova.com/news/stories/2/2003/04/29/story004.html

  44. Polio’s Effects http://www.bret.org.uk/nec2.htm http://cha.state.md.us/edcp/html/polio.html

  45. Hepatitis A (HA) Symptoms • fatigue • jaundice • abdominal pain • loss of appetite • nausea • diarrhea • fever

  46. Persons at Risk • Household contacts of infected persons • Sex contacts of infected persons • Persons, especially children, living in areas with increased rates of hepatitis A during the baseline period from 1987-1997. • Persons traveling to countries where hepatitis A is common • Men who have sex with men • Injecting and non-injecting drug users

  47. Average reported cases of hepatitis Aper 100,000 population*, 1987-1997 Red> 20

  48. The HA World

  49. TRANSMISSION • “HAV is found in the stool (feces) of persons with hepatitis A.  • HAV is usually spread from person to person by putting something in the mouth (even though it may look clean) that has been contaminated with the stool of a person with hepatitis A. ”

  50. Prevention • “Hepatitis A vaccine is the best protection. • Short-term protection against hepatitis A is available from immune globulin. It can be given before and within 2 weeks after coming in contact with HAV.  • Always wash your hands with soap and water after using the bathroom, changing a diaper, and before preparing and eating food.”

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