Microbiolgy Lecture 3

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Microbiolgy Lecture 3
2013-10-17 22:51:48
Bio 474

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  1. Explain these ways to measure growth ?

    spread plate method,
    pour plate method–
    Colony counter–
    Cell Counts–
    Petroff-Hausser counter
  2. How do you use this formula ?

    The doubling time is 20 minutes at 37oC. The bacteria have been incubating for 8 hours, which means there will be doubling taking place 3 times an hour. So there will be (8 hrs x 3) = 24 doubling moments taking place.There will be 24 generations of bacteria after 8 hours.

    • 5000 x 224 = Nt
    • Nt  = 83,886,080,000
    • or 8.388 x1010

    Utilizing the equation Nt=No x 2n

    • Nt=population size at specified time
    • No= initial population size
    • n= # of generations
  3. What is an 

    Obligate aerobe: 
    Aerobe: organism that grows in the presence of oxygen

    Obligate aerobe: requires atmospheric oxygen (20% O2) for growth and metabolism

    Microaerophile :requires O2 for metabolism, but at very low concentrations
  4. What is an 

    Anaerobe :
    Obligate anaerobe:
    Facultative anaerobe:
    Anaerobe: organism that grows in the absence of oxygen

    Obligate anaerobe:cannot grow in the presence of oxygen

    Facultative anaerobe: able to use both pathways; therefore, does not require O2 , but grows better in its presence–

    Aerotolerant: does not require O2 but can withstand the presence of O2; grows just as well in and out of the presence of O2
  5. Where do each of these grow in a test tube culture ?

    Obligate aerobe
    Facultative anaerobe
    Obligate anaerobe
    Obligate aerobe : Top growth

    Facultative anaerobe: Full column

    Obligate anaerobe: bottom growth

    Microaerophile : Middle growth

    Aerotolerant : Full column
  6. What are the important enzymes that destroy free radicals ?
    • Catalase:
    • Peroxidase:
    • Superoxide Dismutase:
    • Superoxide dismutase & catalase:
    • Superoxide reductase:
  7. What are Cytochromes and Siderophores ?
    –Cytochromes: proteins involved in electron transport and redox reactions

    -Siderophores: organic molecules that bind to Fe3+ making it possible for the cell to take up iron
  8. What is the purpose Hydroxamic acid and Enterbactins in the function of bacteria ?
    Hydroxamic acid: strongly chelates iron–

    Enterobactins: produced by enteric bacteria like E. coli and Salmonella
  9. How do the two different photosynthesis differ ?
    Differ in the wavelengths at which light is absorbed

    Cyclic photophosphorylation–the electrons return to the chlorophyll after passing through the electron transport chain

    Non-cyclic photophosphorylation–the electrons are used to reduce NADP and electrons are returned to chlorophyll from H2O and H2S
  10. In terms of Oxygenic vs. Anoxygenic photosynthesis ,Which is for (Chlorophyll or bacteriochlorophyll) ?

    Which one has water as the electron donor ?Which one produces oxygen?
    Which one is frequently and aerobic process?
    • Oxygenic = Chlorophyll
    • Anoxygenic=Bacteriochlorophyll

    • Oxygenic = water as electron donor
    • Oxyegnic= produces oxygen
    • Oxygenic = frequently aerobic
  11. What does a porphyrin do in chlorophyll ?
    What colors does it absorb and transmit?
    • It binds to Mg2+
    • Absorbs light red and blue light; transmits green light
  12. What are the absorption spectrums for  Chlorophyl a  and Chlorophyl b?
    Which is the most common ?

    Which one does alage use ?
    680nm and 660nm 

    680nm is the most common

  13. Where are thykaloid cells located in Eukaryotes and Prokaryotes ?

    Eucaroytes: Occurs in thykaloid membranes within the chloroplast•Procaryotes: Occurs in thykaloid membranes within the cell
    Eucaroytes: Occurs in thykaloid membranes within the chloroplast

    Procaryotes: Occurs in thykaloid membranes within the cell
  14. what is the final electron acceptor in a bacteriochlorophyll ?
  15. What type of bacteria use bacteriochlorophyll ?
    Blue and Green bacteria
  16. Where is the bacteriochlorophyll located in the following bacteria.

    Purple bacteria: 
    Green bacteria:
    Purple bacteria: invagination of the cytoplasmic membrane–

    Heliobacteria: cytoplasmic membrane (unique)–

    Green bacteria: both cytoplasmic membrane and membrane-enclosed structures called chlorosomes
  17. what are carotenoids ?
    • -Most widespread; associated with chlorophyll or bacteriochlorophyll
    • –Hydrophobic pigments firmly embedded in the membrane
    • –Oxygenic photosynthesis: Typically yellow, green, red, brown

    –Anoxygenic photosynthesis: Typically red, purple, pink, green, yellow, brown

    –Do not function in ATP synthesis

    –Transfer light to the reaction centers•Reaction centers are a complex of pigments used to harvest light and generate ATP

    –Act as photoprotective agents from toxic oxygen species (e.g. singlet oxygen)
  18. What are Phycolbilins / Phycobiliproteins ? 
    What bacteria usually has them ?
    Phycobilins/Phycobiliproteins–Present in cyanobacteria and red algal chloroplast

    –Red (phycoerythrin) or blue (phycocyanin) pigments

    –Allophycocyanin (red pigment)•Occur in aggregates called phycobilisomes, attached to the photosynthetic membranes

    Usually seen in serratia
  19. What are osmotolerant microbes ?
    What are Halophiles?
    •Osmotolerant: to grow over a wide range of water activity or osmotic concentration.

    •Halophile:require high levels of NaCl  to grow; usually above 0.2M
  20. What are Acidophiles , Neutrophiles , and Alkalophile ?

    what type are usually found in our bodies ?
    Where would the bacteria Helicobacter pylori be?
    • Acidophile: pH 0 and pH 5.5
    • Neutrophile:  pH 5.5 and pH 8.0
    • Alkalophile: pH 8.5 and pH 11.5

    Neutrophiles are usually in our bodies

    Helicobacter pylori would be an acidophile
  21. What is a 


    Which tend to live in the human body ?
    • Psychrophile– 0-15oC
    • Psychrotroph– 20-30oC; minimum range:
    • 0-7oC; maximum: 35oC.
    • Mesophile–o20-45oC
    • Thermophile–55-65oC
    • Hyperthermophile (extreme thermophile):80-113oC

  22. What is the difference between Barotolerant and Barophile ?
    Barotolerant–able to grow at different ranges of hydrostatic pressures

    Barophile–Grows more rapidly at high hydrostatic pressures