Week 2: Bacterial Reproduction and Growth

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jlyip89
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257308
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Week 2: Bacterial Reproduction and Growth
Updated:
2014-01-18 22:23:13
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Bacteria reproduction growth
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micro
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micro lecture week 2
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  1. Binary fission
    Binary fission (simple division)

    –form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size
  2. Steps of Binary Fission
    1. Cell elongates and DNA is replicated

    2. Cell wall and plasma membrane begin to divide

    3. Transverse septum (wall, cross-wall) forms completely around divided DNA

    (a) due to continued growth of cell wall and membrane

    • (b) divides contents of cell and DNA
    • molecules

    4. Cells separate
  3. Bacterial Growth Curve

    - what are the phases?
    - characteristics of each phase?
    Lag phase: no change in number of cells, metabolically getting ready but not yet dividing

    Log (or exponential) phase:bacteria grow in steady state, no cell death

    Stationary phase: rate of reproduction = rate of death

    Death phase: cells dying in steady state
  4. Which phase of the cell cycle is most sensitive to antibiotics?
    • Log phase bc antibacterial target biosynthesis of
    • bacteria
  5. 6 Requirements for bacterial growth
    (Factors affecting bacterial growth)
    1)Temperature

    2)pH

    3)Oxygen

    4)Water 

    5)Light

    6)Nutrients
  6. Temperature

    - how does it contribute to Bacterial Growth?
    - 3 groups?
    Optimum temp. - temp. at which maximum growth occurs

    • 3 groups:
    • 1. Thermophiles: 45°C - 110°C
    • (e.g. hot springs, volcanoes in ocean, decomposers)

    • 2. Mesophiles: 20°C - 45°C
    • (e.g. environmental bacteria, pathogen)

    • 3. Psychrophiles: 0°C  - 20°C
    • (e.g. cold springs, lakes; polar regions; refrigerator)
  7. Most pathogens fall into what group of temperature bacteria?

    A) thermophiles
    B) psychrophiles
    C) mesophiles
    C) mesophiles
    (this multiple choice question has been scrambled)
  8. pH

    - how does it contribute to bacterial group?
    - 3 groups
    - Optimum pH - pH at which maximum growth occurs

    • 3 groups
    • 1. Alkalinophiles: 8 to 12
    • (e.g. Soil bacteria)

    2. Neutrophiles: 5 to 8

    • 3. Acidophiles: 0 to 5
    •  (e.g. Helicobacter pylori - stomach ulcers)
  9. Most pathogens belong in what pH group?

    A) alkalinophiles
    B) acidophiles
    C) neutrophiles
    C) neutrophiles
    (this multiple choice question has been scrambled)
  10. Bacterial Growth: Oxygen

    - name the 5 groups and its characteristics
  11. Name the following Oxygen Groups:
    1.Obligate

    2.Obligate anaerobic

    3.Facultative

    4.Microaerophile

    5. Aerotolerant anaerobic
  12. Name 3 enzymes the detoxify oxygen radicals

    - groups that each enzyme works on
    • 1. superoxide dismutase
    • - obligate aerobes
    • - facultative anaerobes (most)
    • - aerotolerant anaerobes (most)

    • 2. peroxidases
    • - aerotolerant anaerobes (most)

    • 3. catalase
    • - obligate aerobes
    • - facultative anaerobes (most)

  13. water

    - how it contributes to bacteria growth
    All metabolically active bacteria require water

    –Cells largely water

    –Most nutrients, wastes soluble in water to cross cell membrane.

    –Site of metabolic reactions (cytoplasm)
  14. Bacteria Growth:

    groups that require light?
    groups where light is lethal?
    Very small group photosynthetic bacteria (cyanobacteria)  -  require UV light

    - Nonphotosynthetic bacteria (eubacteria)  -  UV light is lethal (causes mutations)
  15. Name 5 nutritional requirements for bacteria growth
    Basic requirements for growth:

    1. Carbon:building blocks of cell components

    2. Nitrogen: production of proteins, nucleic acids

    3. Hydrogen: occur in organic compounds

    4. Oxygen:  involved in the production of energy

    5: Minerals, trace elements: required in small amounts
  16. autorophs

    - subgroups
    - uses inorganic CO2 as a Carbon source

    - making of own food by reducing CO2

    - "self feeders"

    • subgroups
    • - photoautotrophs
    • -chemoautotrophs
  17. heterotrophs

    - subgroups
    - uses organic compounds as Carbon source

    - using ready-made organic molecules for food

    - "other -feeders"

    • subgroups:
    • - photoheterotrophs
    • - chemoheterotrophs
  18. chemoheterotrophs

    energy source?
    examples?
    organic compound = energy source

    • ex:
    • - most bacteria
    • - all protozoans
    • - all fungi
    • - all animals

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