BIOL41 Lab Exam3

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daynuhmay
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BIOL41 Lab Exam3
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2012-11-20 19:44:12
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BIOL41 Lab Exam#3
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  1. What are the 3 genera of pathogenic cocci discussed?
    • 1) Staphylococcus
    • 2) Streptococcus
    • 3) Neisseria
  2. Is Staphylococcus Gram positive or Gram negative?
    Gram positive
  3. 2 species of Staphylococcus discussed
    • 1) S. epidermidis
    • 2) S. aureus
  4. S. epidermidis
    • Staphylococcus epidermidis
    • typically not pathogenic unless in blood stream
    • NOT hemolytic
    • found on skin

    causes opportunistic infections
  5. S. aureus
    • Staphylococcus aureus
    • 1/3 of people are carriers
    • not always pathogenic
    • found on skin, mucus membranes
    • hemolytic

    causes TSS (toxin mediated), cutaneous diseases
  6. Are Streptococcus Gram positive or Gram negative?
    Gram positive
  7. Where is Streptococcus normally found?
    respiratory tract
  8. Lancefield system of classification
    • classification of B-hemolytic Strep
    • based on carbohydrates in their cell walls
    • groups A-G normally infect people
  9. prototypical Group A Streptococcus
    S. pyogenes
  10. 3 species of Strep discussed
    • 1) S. pyogenes
    • 2) S. pneumoniae
    • 3) Enterococcus faecalis
  11. S. pyogenes
    • Strep pyogenes
    • can lead to Scarlet fever, strep throat, tonsilitis
    • B-hemolytic
  12. S. pneumoniae
    • lives in lungs
    • causes pneumonia
  13. Enterococcus faecalis
    • discussed in Strep group
    • looks like Strep, but chemically not
  14. Are Neisseria Gram positive or negative?
    Gram negative
  15. Neisseria cell morphology/arrangement
    diplococci
  16. typical human location of Neisseria
    mucous membranes
  17. 2 species of Neisseria discussed
    • 1) N. gonorrhoeae
    • 2) N. meningitidis
  18. selective vs differential media
    • selective encourages/discourages growth of specific organisms
    • differential allows visual distinguishment between organisms
  19. What type of medium is blood agar?
    • differential
    • detects hemolytic ability of Gram(+) cocci
  20. hemolysins
    • exotoxins that destroy red blood cells and hemoglobin
    • produced by several species of Gram(+) cocci
  21. -hemolysis
    • complete destruction of RBCs and hemoglobin
    • results in clearing of medium around colonies
  22. -hemolysis
    • partial destruction of RBCs
    • produces greenish discoloration of agar around colonies
  23. -hemolysis
    • non-hemolysis
    • appears as simple growth with NO change to the medium
  24. What would you use PEA agar for?
    isolating Gram(+) organisms
  25. Is PEA selective, differential, or both?
    • selective
    • only encourages growth of Gram(+) organisms
  26. PEA
    • phenylethyl alcohol agar
    • alcohol breaks down Gram(-) membrane permeability barrier
  27. MSA 
    • mannitol salts agar
    • mannitol provides substrate for fermentation
    • high salt concentration
  28. Is MSA selective, differential, or both?
    • both
    • differential: phenol red changes to yellow when pH<6.8
    • selective: high [NaCl] dehydrates/kills most bacteria

    • most staphylococci thrive but don't ferment
    • isolation/differentiation of S. aureus 
  29. bile esculin test
    • Group D strep test
    • isolate/differentiate enterococci
    • broken down bile reacts with Fe and forms dark brown ppt
  30. Is the bile esculin test selective, differential, or both?
    • both
    • differential: changes dark brown if esculin hydrolyzed
    • selective: organisms can tolerate bile
  31. coagulase test
    • differentiates types of Staph that can/cannot clot plasma
    • made of plasma

    typically used to differentiate S. aureus from other Gram(+) cocci
  32. Why would an organism need coagulase?
    • Coagulase works in conjunction with normal plasma
    • components to form protective fibrin barriers around
    • individual bacterial cells or groups of cells, shielding
    • them from phagocytosis and other types of attack.
  33. catalase
    converts hydrogen peroxide into water and O2(g)

    helps organisms live in environments with O2
  34. catalase test
    can identify aerobic and facultatively anaerobic bacteria that use oxygen as an electron acceptor

    • Staph. are catalase-positive
    • Strep. are catalase-negative
  35. oxidase test
    identifies presence of Cyt c oxidase

    Neisseria is oxidase-positive
  36. mycosis
    fungal infection
  37. How do fungi obtain nutrients?
    secrete exoenzymes into environment, then absorb digested nutrients
  38. saprophyte/saprobe
    fungus that decomposes dead organic matter
  39. What are fungal cells made of?
    chitin (polysaccharide)
  40. 2 major types of fungi
    • 1) yeasts (unicellular)
    • 2) molds (filamentous)
  41. thallus
    undifferentiated vegetative tissue
  42. hyphae
    idividual fungal filaments
  43. mycelia
    collective groups of hyphae
  44. dimorphic fungi
    have both mold and yeast life cycle stages

    ex: Candida albicans
  45. How do yeasts typically reproduce?
    • asexual reproduction
    • blastoconidia (buds)
  46. sporangiospores vs conidiospores
    sac vs no sac

    pomegranate vs dandelion
  47. blastoconidia
    budded cell of yeast
  48. Where does Candida albicans normally live?
    • 1) respiratory 
    • 2) GI 
    • 3) female urogenital tracts
  49. Is C. albicans yeast or mold?
    dimorphic yeast
  50. What kinds of mycoses does C. albicans cause?
    thrush (mouth), vulvovaginitis (vagina), cutaneous cadidiasis (skin)
  51. Aspergillus
    • mold
    • common in soil
    • conidiophores (no sac)
  52. Penicillium
    • mold
    • produces antibiotic penicillin
    • conidiophores (no sac)
  53. Rhizopus
    • mold
    • spoils a lot of food
    • sporangiophores (sac)
    • can cause zygomycosis
  54. What characteristics are shared by all protozoa?
    • 1) unicellular
    • 2) heterotrophic
    • 3) trophozoite and cyst stages
    • 4) no cell wall
    • 5) eukaryotic
  55. 3 mechanisms by which protozoans can move
    • 1) pseudopodia
    • 2) cilia
    • 3) flagella
  56. trophozoite vs cyst
    • trophozoite: vegetative state; eating/reproducing/moving
    • cyst: resting state; survives in adverse environments
  57. Entamoeba histolytica (disease caused, how it moves, how it spreads)
    • amebiasis (amoebic dysentery)
    • pseudopodia
    • fecal-oral contact or contaminated water
  58. Balantidium coli (disease caused, how it moves, how it spreads)
    • balantidiasis, dysentery
    • ciliate
    • cysts in sewage-contaminated water
  59. Giardia lamblia (disease caused, how it moves, how it spreads)
    • giardiasis (persistent, blood diarrhea)
    • flagellate
    • fecally contaminated water/food
  60. Trichomonas vaginalis (disease caused, how it moves, how it spreads)
    • trichomoniasis
    • flagellate
    • sexually transmitted
  61. Plasmodium spp (disease caused, how it moves, how it spreads)
    • malaria
    • gliding motility?
    • spreads through mosquitoes
  62. Toxoplasma gondii (disease caused, how it moves, how it spreads)
    • toxoplasmosis
    • gliding motility?
    • ingestion of oocytes in feces
  63. 3 general types of parasitic helminths
    • 1) cestodes (tapeworms)
    • 2) trematodes (flukes)
    • 3) nematodes (roundworms)
  64. cestodes seen in class
    • Dipylidium caninum
    • tapeworm
  65. scolex
    head of the tapeworm that attaches to host
  66. proglottid
    • segment of tapeworm (cestode) that contains reproductive structures and/or eggs
    • migrate out of animal and are ingested by others
  67. helminth cuticle
    outer covering
  68. trematode
    • fluke
    • ex: Schistosoma mansoni
  69. nematode
    • roundworm
    • ex: hookworms, pinworms, Ascaris lumbricoides
  70. Diplydium caninum (disease caused, host organism, how infected)
    • abdominal discomfort, indigestion
    • dogs, cats, children
    • ingestion of flea that ate proglottid
  71. Echinococcus granulosus (disease caused, host organism, how infected)
    • cyst fluid can cause anaphylactic shock
    • carnivore (herbivore intermediary)
    • ingestion leads to cyst formation in organ
  72. Ascaris lumbricoides (disease caused, host organism, how infected)
    • inflammation of organ, pneumonia, blockage/damage of organs
    • humans
    • juveniles reside in lungs, coughed up and transported to GI tract to mature
  73. Necator americanus (disease caused, host organism, how infected)
    • (hookworm)
    • bloody diarrhea, anemia
    • humans
    • juveniles penetrate skin, enter blood, travel to lungs; coughed up and transported to GI tract to mature

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