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Microbiology (Bio305) > Chapter 5 > Flashcards

Chapter 5 Flashcards

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1
Q

What are the “normal” growth conditions?

A
  1. Sea level
  2. 20ºC-40ºC
  3. A near-neutral pH
  4. .9% salt and ample
    nutrients
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2
Q

What are organisms that inhabit ecosystems outside of the “normal” conditions called?

A

extremophiles

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3
Q

What allows us to study the biology of organisms that we cannot culture?

A

Bioinformatic Analysis

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4
Q

A bacterial cell’s temperature matches that of..?

A

its immediate environment

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5
Q

True or False. Changes in temperature impact only some aspects of microbial physiology.

A

False. It impacts every aspect

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6
Q

Microbes that grow at higher temperature can typically…

A

higher rates of growth

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7
Q

The growth rate roughly doubles for every___ ºC

A

10ºC

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8
Q

Thermophiles’ Characteristics

A 
1. They are not easily 
    unfold as those of 
    mesophiles
2. They do not have 
    high amount of 
    glycine
3. The N-terminus of 
     the enzyme is 
     anchored to the 
     other parts of the 
     enzyme
4. They have 
    chaperones
5. They have DNA-
    binding proteins.
6.They have more 
   saturated fatty acids 
   in the membrane.
7. They have 
    monolayers.
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9
Q

What organism’s regular growth temperature is 0ºC-20ºC?

A

Psychrophiles

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10
Q

What organism’s regular growth temperature is 15ºC-45ºC?

A

Mesophiles

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11
Q

What organism’s regular growth temperature is 40ºC-80ºC?

A

Thermophiles

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12
Q

What organism’s regular growth temperature is 65ºC-121ºC?

A

Hyperthermophiles

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13
Q

What causes heat-shock response?

A

Rapid temperature changes experienced during growth activates batcher of stress response genes.

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14
Q

What does chaperones do?

A

maintain protein shape

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15
Q

What do enzymes do?

A

change membrane lipid composition

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16
Q

What are psychrotolerants?

A
  1. grow on old food in the fridge

2. Spoils milk

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17
Q

What are organisms that have adapted to grow at very high pressures? (up to 1,000 atm or 101 MPa or 14,600 psi)

A

Barophiles or piezophiles

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18
Q

What are organisms that grow well over the range of 1-50 MPa, but their growth falls off thereafter?

A

Barotolerant

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19
Q

Barophiles are also ________ because the average temperature at the ocean floor is 2ºC.

A

Psychrophiles

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20
Q

What reduces membrane fluidity?

A
  1. increased hydrostatic
    pressure
  2. Cold temperature
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21
Q

What can counter act the reduction of membrane fluidity?

A

protein structures

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22
Q

What is a measure of how much water is available for use?

A

Water activity (aw)

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23
Q

Most bacteria require water activity levels>__.

A

.91

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24
Q

Fungi can tolerate water activity levels>___.

A

.86

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25
Q

What is water activity typically measured as?

A

the ratio of the solution’s vapor pressure relative to that of pure water

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26
Q

What is a measure of the number of solute molecules in a solution and is inversely related to aw?

A

Osmolarity

27
Q

Why is osmolarity important to the plasma membrane in cells?

A 
1. Allows water to pass 
   but not solutes
2. For a cell in a 
    hypertonic medium, 
    water will leave the 
    cell in an attempt to 
    equalize osmolarity 
    across the membrane 
3. In contrast, 
    suspending a cell in a 
    hypotonic medium 
    will cause an influx of 
    water
28
Q

Why is osmolarity important to the plasma membrane in cells?

A 
1. Allows water to pass 
   but not solutes
2. For a cell in a 
    hypertonic medium, 
    water will leave the 
    cell in an attempt to 
    equalize osmolarity 
    across the membrane 
3. In contrast, 
    suspending a cell in a 
    hypotonic medium 
    will cause an influx of 
    water
29
Q

What are membrane-channel proteins that allow water to transverse the membrane much faster than by diffusion?

A

Aquaporins

30
Q

Hypertonic

A
  • solute concentration is
    higher outside the cell
    -water rushes out of the
    cell
31
Q

Hypotonic

A
  • solute concentration is
    higher inside the cell
  • water rushes into the
    cell
32
Q

What are two mechanisms microbes have to minimize osmotic stress?

A 
1. In hypertonic media, 
   bacteria protect their 
   internal water by 
   synthesizing or 
   importing compatible 
   solutes
2. In hypotonic media, 
   pressure-sensitive or 
   mechanosensitive 
   channels can be used 
   to leak solutes out of 
   the cell.
33
Q

What causes the two mechanisms to become ineffective at controlling internal osmolarity?

A

When they are outside their osmotic comfort range

34
Q

What type of microbe requires high salt concentrations?

A

Halophiles

35
Q

Halophiles need _____ % NaCl while the seawater is ___ % NaCl

A

10-20%

3.5%

36
Q

What is the normal salt requirement?

A

.5-5%

37
Q

How do halophiles achieve a low internal concentration?

A

They use special ion pumps to excrete sodium and replace it with other cations, such as K+

38
Q

What organisms grow at pH 5-8?

A

Neutralophiles (include most pathogens)

39
Q

What organisms grow at pH 0-5?

A

Acidophiles(are often chemoautotrophs)

40
Q

What organisms grow at pH 9-11?

A

Alkaliphiles (typically found in soda lakes)

41
Q

Is moist heat or dry heat more effective at killing microbes?

A

Moist Heat

42
Q

What temperature does water have to be to kill most cells?

A

100ºC (Boiling temp)

43
Q

What does killing spores and thermophiles usually require?

A

a combination of high pressure and temperature.

44
Q

How does the steam autoclave kill microbes?

A
  • 121ºC at 15 psi for 20
    minutes
  • Conditions produced in pressure cookers when canning vegetables
45
Q

How does Pasteurization kill microbes?

A
  • LTLT(low temperature/ long time) : 63ºC for 30 minutes

- HTST(high temperature/ short time): 72ºC for 15 seconds

46
Q

How does Cold kill microbes?

A 
- low temperatures slow growth and preserve strains
Refrigeration Temperatures(4ºC-8ºC) are used for food preservation
- For long-term storage of cultures (lyophilization or freeze-drying)
47
Q

How does filtration kill microbes?

A
  • Micropore filters with pore sizes of .2 um can remove microbial cells, but not viruses, from solutions.
48
Q

Can air be sterilized by filtration?

A

Yes, this process forms the basis of several personal protective devices.

49
Q

What are Laminar flow biological safety cabinets?

A
  • force air through HEPA filters, which remove > 99.9% of airborne particulate material .3 um in size or larger.
50
Q

What does newer technologies embed in the fibers of the filter?

A
  • Antimicrobial agents or enzymes
51
Q

How does Irradiation kill microbes?

A 
- Ultraviolet light: poor 
  penetrating power; 
  used only for surface 
  sterilization
- Gamma Rays, electron 
  beams, and X-rays: 
  high penetrating 
  power; used to 
  irradiate foods and 
  other heat-sensitive 
  items
52
Q

What bacteria is nickname “Conan the bacterium” and why?

A
  • Deinococcus radiodurans
  • has the greatest ability
    to survive radation of
    any known organism
  • Has exceptional
    capabilities for
    repairing DNA
    damaged by radiation
  • Was genetically
    engineered for use in
    bioremediation
53
Q

What are the factors that influence the efficacy of a given chemical agent?

A 
- presence of organic 
  matter
- the kinds of organisms 
  present
- Corrosiveness
- Stability, odor, and 
  surface tension
54
Q

What is the test called that compares the effectiveness of disinfectants?

A
  • Phenol coefficient

Test

55
Q

What are examples of commercial disinfectants and antiseptics?

A
  • Ethanol
  • Iodine (Wescodyne
    and Betadine)
    -Chlorine
    -Ethylene Oxide (a gas
    sterilant)
56
Q

What do commercial disinfectants and antiseptics do?

A 
- Damage proteins, 
  lipids, and/or DNA
- Are used to reduce or 
  eliminate microbial 
  content from objects
57
Q

Can bacteria develop resistance to disinfectants?

A

Yes

58
Q

What are the mechanisms that bacteria use to become resistant to disinfectants?

A
  • Altering the fatty acid synthesis protein normally targeted by triclosan
  • Producing membrane- spanning, multidrug efflux pumps
  • Forming multi-species biofilms, which offer collaborative protection
59
Q

What are chemical compounds synthesized by one microbe that kill or inhibit the growth of other microbial species?

A

Anitbiotics

60
Q

What prevents cell wall formation and is bactericidal?

A

Penicillin

61
Q

What mimics a part of the cell wall to kills the cells?

A

Penicillin

62
Q

What is the use of one microbe to control the growth of another called?

A

Biocontrol

63
Q

What contains certain microbes that, when ingested, to aim to restore balance to intestinal flora?

A

Probiotics

64
Q

What aims to treat infectious diseases with a virus targeted to the pathogen?

A

Phage therapy

Microbiology (Bio305) (7 decks)

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