Microbiology 351 Exam 1 Flashcards - Set 11

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  1. _____ _____ (____) is a measure of how much water is available for use.
    Water activity (aw)
  2. Water activity is typically measured as the ratio of the solution's _____ _____ relative to that of pure water.
    vapor pressure
  3. Most bacteria require water activity levels > _____.
  4. Fungi can tolerate water activity levels > ____
  5. _____ is a measure of the number of solute molecules in a solution and is ______ related aw
    Osmolarity, inversely
  6. ______ are membrane-channel proteins that allow water to traverse the membrane much faster than by diffusion.
    - Helps protect the cell form osomtic stress
  7. In hypertonic media, bacteria protect their internal water by synthesiszing or importing _____ _____ (e.g. proline or K+)
    compatible solutes
  8. In hypotonic media, pressure-sensitive or _______ channels can be used to leak solutes out of the cell.
  9. ______ require really high salt concentrations.
    - From __ to __ M NaCl (10-20% NaCl)
    - For comparison, seawater is ~____% NaCl
    • Halophiles
    • - 2 to 4
    • - 3.5
  10. To achieve a low internal concentration of Na+, halophilic microbes use special ____ ____ to excrete sodium and replace it with other cations, such as ____.
    ion pumps, K+
  11. Aerobic repsiration uses oxygen as a terminal electron acceptor (TEA) in the ____ ____ ____.
    electron transport chain
  12. Oxygen is toxic to all cells that do not have enzymes capable of efficiently destroying the _____ ____ _____ (ROS) - for example, anaerobes.
    reactive oxygen species
  13. Three oxygen-removing techniques are used today:
    1. Special ______ ____ (thioglycolate) or ____ systems (Oxyrase) can be added to ordinary liquid media.
    2. An ______ jar
      - O2 is removed by a reaction catalyzed by _______
    3. An anaerobic ______ with glove ports
      - O2 is removed by vacuum and replaced with ____ and _____
    • 1. reducing agents, enzyme
    • 2. anaerobe, palladium
    • 3. N2, CO2
  14. Starvation is a stress that can elicit a "______ response" in many microbes.
    - ______ are produced to increase the efficiency of nutrient gathering and to protect cell macromolecules from damage.
    starvation, enzymes
  15. The "starvation response" is usually triggered by the accumulation of small _____ _____ such as cAMP or guanosine tetraphosphate, which globally transform gene expression.
    signal molecules
  16. True/False: Small signal molecules such as cAMP and guanosine tetraphosphate are not soluble and cannot diffuse throughout the cell.
    False, these highly soluble, small molecules can quickly diffuse throughout the cell, promoting a fast response time.
  17. Natural ecosystems are typically low in nutrients (_______). Maximum diversity is maintained in part, by the different nutrient-gathering profiles of ______ microbes.
    oligotrophic, competing
  18. ______ is the sudden infusion of large quantities of a formerly limiting nutrient.
    - it can lead to a "bloom" of microbes, which can threaten the existence of competing species.
  19. Name the antimicrobial control measure:
    - killing of all living organisms
  20. Name the antimicrobial control measure:
    - killing or removal of pathogens from inanimate objects
  21. Name the antimicrobial control measure:
    - killing or removal of pathogens from the surface of living tissues
  22. Name the antimicrobial control measure:
    - reducing the microbial population to safe levels
  23. High temperature kills microbes.
    - _____ heat is more effective than ____ heat
    - _____ water (____°C) kills most cells
    - Killing _____ and ____ usually requires a combination of high pressure and temperature.
    - Steam autoclave: ____°C at ___ psi for ___ minutes
    • - moist, dry
    • - boiling, 100
    • - spores, thermophiles
    • - 121, 15, 20
  24. Pasterurization kills microbes. Many different time and temperature combinations can be used.
    - LTLT (low temperature/long time): ____°C for ___ minutes
    - HTST (high temperature/short time): ____°C for ___ seconds
    • - 63, 30
    • - 72, 15
  25. Cold/Low temperatures slow growth and preserve microbe strains.
    - Refrigeration temperature (___-___°C) are used for food preservation
    - For long-term storage of cultures:
      - placing solutions in glycerol at _____°C
      - Lyophilization or ____-______
    • - 4-8
    • - -70
    • - freeze-drying
  26. Micropore filters with pore sizes of ____ μm can remove microbial cells, but not viruses, from solutions.
  27. Samples from ___ mL to several ____ can be drawn through a membrane filter by vacuum or can be forced through it using a syringe.
    1, liters
  28. Laminar flow biological safety cabinets force air through HEPA filters, which remove > ____% of airborne particulate material ____ μm in size or larger.
    99.9, 0.3
  29. Irradiation kills microbes.
    - Ultraviolet light has ____ penetrating power and is used only for ______ sterilization
    - Gamma rays, electron beams, and X-rays have ____ penetrating power are are used to irradiate ____ and other heat-sensitive items.
    • - poor, surface
    • - high, foods
  30. Deinococcus radiodurans has the greatest ability to survive radiation of any known organism. It has exceptional capabilities for _____ ____ damaged by radiation. It was genetically engineered for use in _______.
    repairing DNA, bioremediation
  31. The ______ coefficient test compares the effectiveness of disinfectants.
  32. Commericial disinfectants and antiseptics include ethanol, iodine, chlorine, ethylene oxide, which damage _____, _____ and/or ____.
    proteins, lipids, DNA
  33. Bacteria have developed resistance to disinfectants via several mechanisms:
    - Altering the _____ ____ synthesis protein normally targeted by triclosan
    - Producing membrane-spanning, multidrug ____ pumps
    - Forming multispecies _____, which offer collaborative protection
    • - fatty acid
    • - efflux
    • - biofilms
  34. ______ are chemical compounds synthesized by one microbe that kill or inhibit the gorwth of other microbial species.
  35. ______ mimics part of the bacterial cell wall which prevents the cell wall formation and is bactericidal.
  36. Antibiotics can target:
    - ______ synthesis
    - DNA _______
    - Cell ______
    • - protein
    • - replication
    • - membranes
  37. ______ is the use of one microbe to control the growth of another.
  38. _______ contain certain microbes that, when ingested, aim to restore balance to intestinal flora
    - Lactobacillus and Bifidobacterium
  39. _____ therapy aims to treat infectious diseases with a virus targeted to the pathogen
    - A possible alternative to antibiotics in the face of rising antibiotic resistance
  40. _______ require high salt concentrations.
  41. Name 5 physical agents used to control microbes.
    • 1. Autoclaving
    • 2. Pasteurization
    • 3. Refrigeration
    • 4. Filtration
    • 5. Irradiation
  42. Chemical agents used to control microbes include _____ and _____.
    antiseptics and disinfectants
  43. True/False: Antibiotics selectively control microbial growth.
  44. Biological control of microbes include ____ and _____.
    probiotics, phage therapy
  45. Cells treated with antimicrobials die at a ______ rate.
  46. Which of the following statements about microbes and temperature is FALSE?
    A) within a specific range, the microbial growth rate roughly doubles for every 10°C rise in temperature
    B) thermophiles are microbes that grow at temperatures between 40-80°C
    C) microbes have mechanisms to control their temperature
    D) changes in temperature affect membrane fluidity, and thus nutrient transport
    C) microbes have mechanisms to control their temperature
    (this multiple choice question has been scrambled)
  47. Which of the following is a micronutrient?
    A) carbon
    B) zinc
    C) sulfur
    D) calcium
    E) nitrogen
    B) zinc
    (this multiple choice question has been scrambled)
  48. Human pathogens are:
    A) mesophiles
    B) barophiles
    C) halophiles
    D) psychrophiles
    E) thermophiles
    A) mesophiles
    (this multiple choice question has been scrambled)
Card Set:
Microbiology 351 Exam 1 Flashcards - Set 11
2016-02-12 21:15:59
Control of Bacterial Growth
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