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Microbiology (Bio305) > Chapter 5 > Flashcards

Chapter 5 Flashcards

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
What is water activity typically measured as?
the ratio of the solution's vapor pressure relative to that of pure water
26
What is a measure of the number of solute molecules in a solution and is inversely related to aw?
Osmolarity
27
Why is osmolarity important to the plasma membrane in cells?
``` 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
Why is osmolarity important to the plasma membrane in cells?
``` 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
What are membrane-channel proteins that allow water to transverse the membrane much faster than by diffusion?
Aquaporins
30
Hypertonic
- solute concentration is higher outside the cell -water rushes out of the cell
31
Hypotonic
- solute concentration is higher inside the cell - water rushes into the cell
32
What are two mechanisms microbes have to minimize osmotic stress?
``` 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
What causes the two mechanisms to become ineffective at controlling internal osmolarity?
When they are outside their osmotic comfort range
34
What type of microbe requires high salt concentrations?
Halophiles
35
Halophiles need _____ % NaCl while the seawater is ___ % NaCl
10-20% | 3.5%
36
What is the normal salt requirement?
.5-5%
37
How do halophiles achieve a low internal concentration?
They use special ion pumps to excrete sodium and replace it with other cations, such as K+
38
What organisms grow at pH 5-8?
Neutralophiles (include most pathogens)
39
What organisms grow at pH 0-5?
Acidophiles(are often chemoautotrophs)
40
What organisms grow at pH 9-11?
Alkaliphiles (typically found in soda lakes)
41
Is moist heat or dry heat more effective at killing microbes?
Moist Heat
42
What temperature does water have to be to kill most cells?
100ºC (Boiling temp)
43
What does killing spores and thermophiles usually require?
a combination of high pressure and temperature.
44
How does the steam autoclave kill microbes?
- 121ºC at 15 psi for 20 minutes - Conditions produced in pressure cookers when canning vegetables
45
How does Pasteurization kill microbes?
- LTLT(low temperature/ long time) : 63ºC for 30 minutes | - HTST(high temperature/ short time): 72ºC for 15 seconds
46
How does Cold kill microbes?
``` - 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
How does filtration kill microbes?
- Micropore filters with pore sizes of .2 um can remove microbial cells, but not viruses, from solutions.
48
Can air be sterilized by filtration?
Yes, this process forms the basis of several personal protective devices.
49
What are Laminar flow biological safety cabinets?
- force air through HEPA filters, which remove > 99.9% of airborne particulate material .3 um in size or larger.
50
What does newer technologies embed in the fibers of the filter?
- Antimicrobial agents or enzymes
51
How does Irradiation kill microbes?
``` - 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
What bacteria is nickname "Conan the bacterium" and why?
- 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
What are the factors that influence the efficacy of a given chemical agent?
``` - presence of organic matter - the kinds of organisms present - Corrosiveness - Stability, odor, and surface tension ```
54
What is the test called that compares the effectiveness of disinfectants?
- Phenol coefficient | Test
55
What are examples of commercial disinfectants and antiseptics?
- Ethanol - Iodine (Wescodyne and Betadine) -Chlorine -Ethylene Oxide (a gas sterilant)
56
What do commercial disinfectants and antiseptics do?
``` - Damage proteins, lipids, and/or DNA - Are used to reduce or eliminate microbial content from objects ```
57
Can bacteria develop resistance to disinfectants?
Yes
58
What are the mechanisms that bacteria use to become resistant to disinfectants?
- 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
What are chemical compounds synthesized by one microbe that kill or inhibit the growth of other microbial species?
Anitbiotics
60
What prevents cell wall formation and is bactericidal?
Penicillin
61
What mimics a part of the cell wall to kills the cells?
Penicillin
62
What is the use of one microbe to control the growth of another called?
Biocontrol
63
What contains certain microbes that, when ingested, to aim to restore balance to intestinal flora?
Probiotics
64
What aims to treat infectious diseases with a virus targeted to the pathogen?
Phage therapy

Microbiology (Bio305) (7 decks)

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