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Microbiology > Chapter 1 Lecture 9/14 > Flashcards

Chapter 1 Lecture 9/14 Flashcards

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Biology 101 flashcards
1
Q

Media Type by function (specialized media)

A

General growth media
Enriched media
Selective media
Differential media

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2
Q

Enriched media

A

can be used to increase a particular population of microbes with a specific property from a mixture of cell types

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3
Q

Selective media

A

allows for isolation of microbes with specific properties

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4
Q

Differential media

A

allows certain microbes to be recognized based on visual reactions in the medium

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5
Q

Notes to obtaining a pure culture

A

One of the benefits of a solid medium is that cells are held in place on the surface and can be isolated.
This can lead to separating a mixture of cells into a pure population.
There are 3 methods for separating cells on a plate.

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6
Q

3 methods for separating cells on a plate

A

Streak plate method
Spread plate method
Pour plate method

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7
Q

Nitrogen

A

amino acids, purines, pyrimidines, some carbohydrates, lipids, enzyme cofactors etc.

supplied in numerous ways
-Metabolism of amino acids, nitrates, ammonia, from atmosphere
-Nitrogen Fixation

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8
Q

Phosphorus

A

nucleic acids, phospholipids, coenzymes, some proteins, etc.

Common phosphorous sources
Inorganic phosphate
Organic molecules containing a phosphoryl group

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9
Q

Sulfur

A

amino acids, coenzymes

Obtained from 2 sources
Amino acids cysteine and methonine

Sulfate
-assimilatory sulfate reduction
sulfatesulfitehydrogen sulfide

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10
Q

Growth factors

A

organic compounds that cannot be synthesized by an organism but are essential for growth

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11
Q

3 classes of growth factors

A

1) amino acids -protein synthesis

2) purines/pyrmidines -nucleic acid synthesis

3) vitamins- enzyme cofactors, needed in very small amounts

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12
Q

Nutrient concentration

A

Growth rate –dependent on amounts of nutrients in environment

One key nutrient, available in the lowest amount, will dictate how much growth can occur over time

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13
Q

Aerobes

A

Aerobes grow in the presence of oxygen.

Obligate aerobes REQUIRE oxygen.

Microaerophiles grow best when there is less oxygen than normal.

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14
Q

Anaerobic growth

A

Anaerobic growth occurs without oxygen.

Aerotolerant anaerobes aren’t harmed by oxygen but don’t use it, either.

Obligate anaerobes cannot grow when oxygen is present.

Facultative anaerobes CAN use oxygen but can also grow in the absence of oxygen.

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15
Q

Thioglycolate Broth

A

Reducing compound which shows gradient of compound

Less oxygen at bottom than at top

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16
Q

Obligate aerobe

A
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17
Q

Facultative anerobe

A
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18
Q

Aerotolerant anaerobe

A
19
Q

Strict anaerobe

A
20
Q

Microaerophile

A
21
Q

Factors affecting microbial growth

A

Effects of oxygen on microbial growth

Often determined by what defenses are available against oxygen’s negative effects in the cell

22
Q

Reactive Oxygen Species

A

oxygen easily reduced to toxic reactive oxygen species (ROS)

O2 + e- –> O2- (superoxide radical)

O2- + e- + 2H+ –> H2O2 (hydrogen peroxide)

H2O2 + e- + H+ –> H2O + OH (hydroxyl radical)

23
Q

Enzymes that protect against toxic O2 products

A

Aerobes produce protective enzymes

2O2- + 2H+ –(superoxide dismutase)–> O2 + H2O2

2H2O2 –(catalase)–> 2H2O + O2

H2O2 + NADH + H+ –(peroxidase)–> 2H2O + NAD+

24
Q

Strict Anaerobic Microbes

A

*Strict anaerobic microorganisms lack

  • Superoxide dismutase
  • Catalase

*These microbes cannot tolerate O2

*Anaerobes must be grown without O2

  • work station with incubator
  • gaspak anaerobic system
25
Q

An Anaerobic Workstation

A

Incubator
Airlock
Gloves

26
Q

The GasPak Anaerobic System

A

Catalyst chamber
Gas generator envelope
Lid
Lockscrew
Clamp
Rubber gasket seal
Anaerobic indicator strip

27
Q

pH

A

Effects of pH on microbial growth

Microbes have an optimal pH range for growth.
Acidophiles = pH < 5.5
Neutrophiles = pH 5.5 to 8.5
Alkalophiles = pH > 8.5

28
Q

hypotonic solution

A

(higher osmotic concentration outside)

  • water enters the cell
  • cell swells may burst
29
Q

hypertonic

A

(lower osmotic concentration outside)

  • water leaves the cell
  • membrane shrinks from the cell wall (plasmolysis) may occur
30
Q

halophiles

A

grow optimally in the presence of NaCl or other salts at a concentration above about 0.2M

31
Q

extreme halophiles

A

require salt concentrations of 2M and 6.2M

32
Q

Compatible solutes

A

molecules that can be kept at high internal concentration

33
Q

Solutes and Water Activity

A

water activity (aw)
amount of water available to organisms

Aw of distilled water is 1.0
Aw of milk is 0.97
Aw of dried fruits is 0.5

34
Q

Osmotolerant microbes

A

Osmotolerant microbes can grow over wide ranges of water activity

(e.g., Staphylococcus aureus 3M NaCl)

35
Q

Temperature

A

Effects of temperature on microbial growth

Different microbes have different optimal temperature growth ranges.

36
Q

Cardinal Growth Temperatures

A

Minimal
Maximal
Optimal

37
Q

psychrophiles

A

0 to 20 C

38
Q

psychrotrophs

A

0 to 35 C

39
Q

mesophiles

A

20 to 45 C

40
Q

thermophiles

A

55 to 85 C

41
Q

hyperthermophiles

A

85 to 113 C

42
Q

Resistance to heat denaturation in cells

A

for DNA, more GC will help DNA maintain Hydrogen bonds and prevent some denaturation

43
Q

Cell resistance to extreme cold

A

Everything slows down

Saturation to prevent Ice formation:
H2O in cell freezes into crystals and cuts everything, unless you saturate cells (mix with glycerol) to prevent ice formation, you can prevent death by ice

Structural adaptations

44
Q

Adaptations of Thermophiles

A

protein structure stabilized by a variety of means

histone-like proteins stabilize DNA

membrane stabilized by variety of means
e.g., ether linkages (archaeal membranes)

Microbiology (17 decks)

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