Micro Test 2

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Micro Test 2
2013-03-06 19:10:12
Microbial Growth

Microbial Growth
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  1. Define Phototroph
    use light as energy source ex:plants, some fungi
  2. Define Chemotroph
    use chemicals (nutrients from their environment) as an energy source ex: humans, bacteria
  3. Define Autotroph
    "self feeders" use carbon dioxide as a carbon source
  4. Define Heterotroph
    feeds on others, require an organic carbon source
  5. What are the energy and carbon sources for photoheterotrophs?
    Engery Source: Light; Carbon Source: organic compounds like alcohol, lipids, carbs, organic acids.
  6. What are the energy and carbon sources for photoautotrophs?
    Energy Source: Light; Carbon Source: mainly carbon dioxide.
  7. What are the energy and carbon sources for chemoheterotrophs?
    Energy Source: chemical like glucose or other biomolecules; Carbon Source: Glucose or other biomolecule
  8. What are the energy and carbon sources for chemoautotrophs?
    Energy Source: chemical like hydrogen, sulfide, sulfur, ammonia, nitrite ions, iron, etc; Carbon Source: Carbon Dioxide
  9. What effect does temperature have on microbes?
    most bacteria grow within a limited range of temperatures (about 30 degree range). They have a minimum, optimum and maximum growth temperature.
  10. What are Psychrophiles?
    Cold loving bacteria (15 degrees)
  11. What are Mesophiles?
    moderate temperature loving bacteria (35 degrees)
  12. What are Thermophiles?
    heat loving bacteria (60 degrees)
  13. What are Psychrotrophs?
    cause food spoilage because they grow at refrigeration temperatures
  14. What effect does pH have on microbes?
    Most bacteria grow between pH 6.5 an 7.5. Molds and yeasts grow between pH 5 and 6
  15. What are the different categories of microbes in regard to pH?
    Extreme Acidophiles (0-2), Acidophiles (2-5), neutrophiles (6-8), Alkalophiles (9-11) and Extreme Alkalophiles (12-14).
  16. What happens to bacteria in a hypertonic solution?
    They lose water to their environment and undergo plasmolysis (shrinking away)
  17. What happens to bacteria in a Hypotonic solution?
    The gain water from their environment and lysis (explode)
  18. Why do bacteria need water? What are the exceptions
    Water contains the nutrients they need to grow and they need it for metabolism. Exceptions are extreme or obligate halophiles like halobacterium.
  19. What are carbon, nitrogen, sulfur, phosphorous and trace elements needed for?
    The rest of the dry weight of bacteria. Nitrogen: Protein, DNA/RNA and ATP synthesis; Sulfur: protein and vitamin synthesis; Phosphorous: DNA/RNA, ATP and phospholipid synthesis; Trace Elements: cofactors for enzymes.
  20. What is nitrogen fixation and why is it useful?
    microorganisms able to use nitrogen gas from the atmosphere. Many have symbiotic relationships with plant roots
  21. What effect does oxygen have on microbes? What are the different categories of microbes in regard to oxygen?
    Some microbes require oxygen to grow, others grow in the absence and other are poisoned by it.
  22. Define Obligate Aerobe
    grow only in the presense of oxygen
  23. Define Facultative Anaerobe
    grow with or without oxygen but generally better with
  24. Define Aerotolerant Anaerobe
    essentially ignore oxygen and grow equally well with our without it
  25. Define Obligate Anaerobe
    will die in the presence of oxygen
  26. Define Microaerophiles
    Will not grow at normal atmospheric oxygen concentrations but still require some oxygen (2-10%)
  27. How can an aerobic environment change to an anaerobic environment?
    in the ocean, deeper water and along the bottom, it will become anaerobic as organic debris is decomposed
  28. How are the toxic byproducts superoxide, peroxide, and hydroxyl radicals dangerous to obligate anaerobes?
    they don't have enzymes to get rid of these radicals like aerobes do.
  29. What enzymes protect other organisms from these toxic byproducts?
    Superoxide dismutase and catalase