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Microbio 1010 > Growth & Nutrition > Flashcards

Growth & Nutrition Flashcards

1
Q

What are macronutrients?

A

Elements required in large amounts to build macromolecules

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2
Q

What are the building blocks of proteins?

A

Amino acids

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3
Q

What are the building blocks of lipids?

A

Fatty acids and glycerol

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4
Q

What are the building blocks of carbohydrates?

A

Sugars

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5
Q

Are sugars polar or nonpolar and what does this mean for their solubility?

A

They are polar and soluble

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6
Q

What are the building blocks of nucleic acids?

A

Nucleotides

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7
Q

What do inorganic ions often function as?

A

Metabolic co-factors

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8
Q

What do enzymes involved in protein synthesis require?

A

K+

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9
Q

What do cytochromes (electron carriers) require?

A

Fe2+

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10
Q

What does Mg2+ help stabilize?

A

Membranes and nucleic acids

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11
Q

What does Ca2+ help stabilize?

A

Cell walls and heat

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12
Q

What are micronutrients?

A

Elements required in very small concentrations

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13
Q

What are growth factors?

A

Small organic molecules required for growth

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14
Q

What are the 3 classes of growth factors?

A

1) Amino acids
2) Purines and pyrimidines
3) Vitamins

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15
Q

What is the source of H and O?

A

No specific source, found in H2O and organic media components

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16
Q

What is the source of P?

A

Usually provided as phosphate salt (PO4 3-)

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17
Q

What is a limiting nutrient?

A

Growth will stop when this nutrient runs out

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18
Q

What is the source of inorganic N?

A

Salts (KNO3 or NH4Cl)

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19
Q

What must be done to inorganic nitrogen?

A

Must be reduced to NH3

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20
Q

What is the source of organic N?

A

Amino acids, which is a nitrogen rich organic molecule

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21
Q

What is nitrogen fixation?

A

N2 is reduced to 2NH3

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22
Q

What is NH3 used to make?

A

Amino acids

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23
Q

Which domains can do nitrogen fixation?

A

Bacteria and archaea

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24
Q

What is the source of inorganic S?

A

Salts (MgSO4)

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25
Q

What must be done to inorganic S?

A

Must be reduced to S2-

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26
Q

What is the source of organic S?

A

Amino acids (cysteine and methionine)

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27
Q

What kind of carbon do heterotrophs use?

A

Organic

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28
Q

What kind of carbon do autotrophs use?

A

Inorganic carbon (CO2)

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29
Q

What are 6 classes of culture media?

A

1) Defined medium
2) Minimal medium
3) Complex medium
4) Differential medium
5) Selective medium
6) Enriched medium

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30
Q

Describe defined medium

A

Exact chemical composition is known

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31
Q

What is minimal medium?

A

A defined medium that provides the minimum nutritional requirements for growth (no growth factors)

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32
Q

What does minimal medium allow the growth of?

A

Self-sufficient and “non-picky” microorganisms

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33
Q

Describe complex medium

A
  • Exact chemical composition is not known

- Supply a variety of growth factors

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34
Q

What does differential medium allow for?

A

Different bacteria to be distinguished

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35
Q

What does selective medium contain?

A

Ingredients that inhibit the growth of unwanted microbes

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36
Q

What does enriched medium contain?

A

Special nutrients that encourage the growth of “picky” microorganisms

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37
Q

Define metabolism

A

The sum total of all of the chemical reactions that occur in a cell

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38
Q

Define catabolism

A

Energy-releasing metabolic reaction

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39
Q

Define anabolism

A

Energy-requiring metabolic reactions

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40
Q

What are chemorganotrophs?

A

Microorganisms that get energy from chemical reactions involving organic material

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41
Q

What are chemolithotrophs?

A

Microorganisms that get energy from inorganic chemical reactions

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42
Q

What are phototrophs?

A

Microorganisms that get energy from light

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43
Q

What is growth measured as?

A

An increase in the number of cells

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44
Q

What is binary fission?

A

Cell division following enlargement of a cell to twice its minimum size

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45
Q

What is generation time?

A

Time required for microbial cells to double in number

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46
Q

Is there ever mitosis in bacteria and archaea?

A

No

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47
Q

Do bacteria or eukarya have shorter generation times?

A

Bacteria

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48
Q

What is generation time dependent on?

A

Growth medium and incubation conditions

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49
Q

What is exponential growth?

A

Growth of a microbial population in which cell numbers double at a constant and specific time interval

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50
Q

What is the equation to determine final cell number using initial cell number and number of generations?

A 
Nt = No * 2^n 
(Nt = final cell number; No = initial cell number; n = number of generations)
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51
Q

What must be plot to produce a linear graph of exponential growth?

A

The log scale

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52
Q

What is microorganism growth limited by?

A

Amount of nutrients and build-up of waste

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53
Q

Is exponential growth limited or unlimited?

A

Unlimited

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54
Q

What is growth rate?

A

The rate of increase in population number of biomass

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55
Q

What is growth rate expressed as for bacteria and archaea?

A

Number of doublings per hour

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56
Q

How can growth rate (k) be calculated?

A

k = (log Nt - log No) / (0.301 delta t)

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57
Q

How is generation time (g) calculated?

A

g = 1 / k

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58
Q

What is batch culture?

A

A closed-system microbial culture of fixed volume

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59
Q

What 4 phases are present in a typical growth curve for the population of cells grown in a closed system?

A

1) Lag phase
2) Logarithmic / exponential phase
3) Stationary phase
4) Death phase

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60
Q

What occurs in the lag phase?

A
  • Growth = death

- Nutrient-rich and low waste

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61
Q

What occurs in the logarithmic / exponential phase?

A

Growth > death

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62
Q

What occurs in the stationary phase?

A
  • Growth = death

- Nutrient poor and high waste

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63
Q

What occurs in the death phase?

A

Death > growth

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64
Q

What is a continuous culture?

A

An open-system microbial culture of fixed volume (add nutrients and take away waste at same rate)

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65
Q

What is a chemostat?

A

Most common type of continuous culture device

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66
Q

What is dilution rate?

A

The rate at which fresh medium is pumped in and spent medium is pumped out

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67
Q

What does concentration of a limiting nutrient control?

A

Population size and growth rate

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68
Q

Describe the Petroff-Hausser counting chamber

A

Each square corresponds to a calibrated volume

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69
Q

What are 3 limitations of microscopic counts?

A

1) Cannot distinguish between living and dead cells without special stains
2) Small cells can be overlooked
3) Motile cells need to be immobilized

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70
Q

What does a cytometer use to enumerate cells in a liquid sample?

A

Laser beams, flourescent dyes, and electronics

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71
Q

What is a viable cell count?

A

A measurement of only living cells capable of growing to form a population

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72
Q

What are the two main ways to perform plate counts?

A

1) Spread-plate method

2) Pour-plate method

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73
Q

What is needed to obtain a plate count?

A
  • Preparation and manipulations (dilution tubes, agar plates)
  • Incubation time
74
Q

What is the downside to selective culture media?

A

It only targets particular species

75
Q

Is there a medium that will grow every microbe?

A

Nope

76
Q

What is the great plate anomaly?

A

Direct microscopic counts of natural samples reveal far more organisms than those recoverable on plates

77
Q

How is turbidity measured?

A

A spectrophotometer

78
Q

What is turbidity measured in?

A

Optical density

79
Q

What happens to absorbance and light transmission as the number of particles increases?

A

Absorbance increases and light transmission to the photocell decreases

80
Q

Does absorbance distinguish live and dead cells?

A

Nope

81
Q

What are 3 conditions to make turbidity measurements accurate?

A

1) Cells must be evenly distributed throughout the medium
2) Cuvette must not have scratches
3) Culture may need to be diluted

82
Q

Define cardinal temperatures

A

The minimum, optimum, and maximum temperatures at which an organism can grow

83
Q

What occurs at the minimum temperature that an organism can grow?

A
  • Membrane gelling

- Transport processes so slow that growth cannot occur

84
Q

What occurs at the optimum temperature for an organisms growth?

A

Enzymatic reaction occurring at maximal possible rate

85
Q

What occurs at the maximum temperature that an organism can grow?

A
  • Protein denaturation
  • Collapse of the cytoplasmic membrane
  • Thermal lysis
86
Q

What is a psychrophile?

A

Low growth temperature optimum

87
Q

What is a mesophile?

A

Midrange growth temperature optimum

88
Q

What is a thermophile?

A

High growth temperature optimum

89
Q

What is a hyperthermophile?

A

Very high growth temperature optimum

90
Q

What are 2 examples of mesophiles?

A

1) Warm blooded animals

2) Organisms in terrestrial and aquatic environments

91
Q

What must psychrophiles have to prevent their membrane from gelling?

A

An outer shell

92
Q

What are psychrotolerant organisms?

A

Organisms that can grow at 0 C, but have optima of 20 C - 40 C

93
Q

What are 3 molecular adaptations that support psychrophily?

A

1) Enzymes that function optimally in the cold
2) Modified cytoplasmic membrane
3) High unsaturated fatty acid content (don’t freeze as fast as saturated fatty acids)

94
Q

What life forms exist above 65 C?

A

Only prokaryotic

95
Q

Is there phototrophy above 70 C?

A

No

96
Q

Where are thermophiles typically found?

A

Terrestrial hot springs

97
Q

Where are hyperthermophiles found?

A

Boiling hot springs and seafloor hydrothermal vents

98
Q

What are 2 molecular adaptations to support thermophily?

A

1) Thermal stability for enzymes and proteins

2) Cytoplasmic membrane modifications to ensure heat stability

99
Q

What does bacteria have to support thermophily?

A

Lipids rich in saturated fatty acids

100
Q

What does archaea have to support thermophily?

A

Lipid monolayer

101
Q

Are enzymes of thermophiles or mesophiles more stable?

A

Thermophiles

102
Q

What might be the closest descendants of ancient microbes?

A

Hyperthermophiles

103
Q

What is common to many hyperthermophiles?

A

Oxidation of H2

104
Q

How does pH affect microbial growth?

A

Interactions between R groups of amino acids

105
Q

What are neutrophiles?

A

Organisms that grow best at pH 6 - 8

106
Q

What are acidophiles?

A

Organisms that grow best at pH

107
Q

What are alkaliphiles?

A

Organisms that grow best at pH > 9

108
Q

Give 3 reasons why microbial culture media contain buffers.

A

1) Each organism has an optimal growth pH
2) Some bacteria produce acids, which decreases pH
3) Some bacteria grow on amino acids, releasing ammonia, which increases pH

109
Q

What is water activity?

A

Water availability

-The amount of water that is interacting with ions and polar compounds in solution

110
Q

What is water activity expressed in?

A

A ratio of vapor pressure of air in equilibrium with a substance/solution to the vapor pressure of pure water

111
Q

Between a cytoplasm and the surrounding environment, which typically has a higher [solute] and why?

A

Cytoplasm because it is small and has a lot of solute per unit volume

112
Q

In what direction does water normally move with respect to a cell and its environment and what does this create?

A
  • Into the cell

- Creates turgor pressure

113
Q

What are halophiles?

A

Organisms that grow best at reduced water potential

114
Q

What do halophiles have a specific requirement for?

A

NaCl

115
Q

Give an example of a halophile

A

Many marine microbes

116
Q

What are extreme halophiles?

A

Organisms that require high levels (15 - 30%) of NaCl for growth

117
Q

Give an example of extreme halophiles

A

Microbes from Great Salt lake or the Dead Sea

118
Q

Define halotolerant

A

Can tolerate some reduction in water activity of environment, but generally got best at lower solute concentrations

119
Q

Give an example of a halotolerant organism

A

Staphylococcus aureus

120
Q

What level of NaCl is best for staphylococcus aureus to grow in?

A

Low

121
Q

What are osmophiles?

A

Organisms that can grow with high sugar as solute

122
Q

What are xerophiles?

A

Organisms that can grow in very dry environments

123
Q

What are the 2 rarest categories of organisms?

A

Osmophiles and xerophiles

124
Q

How do organisms combat low water activity in their surrounding environment?

A

Increase internal [solute] by

  • Pumping inorganic ions into cell
  • Synthesizing or concentrating organic solutes
125
Q

What are compatible solutes?

A

Compounds used by cell to counteract low water activity in surrounding environment

126
Q

Define obligate aerobes

A

Require oxygen to live

127
Q

Define strict anaerobes

A

Do not require oxygen and may even be killed by it

128
Q

Define facultative aerobes

A

Can live with or without oxygen; use oxygen when it is available

129
Q

Define aerotolerant anaerobes

A

Can tolerate oxygen and grow in its presence but cannot use it

130
Q

Define microaerophiles

A

Can use oxygen only when it is present at levels reduced from that in air

131
Q

What can be used to distinguish differences in oxygen use/tolerance?

A

Thioglycolate broth

132
Q

Describe the thioglycolate broth of an obligate aerobe

A

Grows only in the oxic zone at the top of the tube

133
Q

Describe the thioglycolate broth of a strict anaerobe

A

Grows only in the anoxic zone at the bottom of the tube

- Will have majority of growth as far down tube as possible

134
Q

Describe the thioglycolate broth of a facultative aerobe

A

Grows throughout the tube

- More growth in oxic zone, steady growth in anoxic zone

135
Q

Describe the thioglycolate broth of a microaerophile

A

Grows in a narrow band between the oxic zone

- Can’t grow too close to the top because it is killed by atmospheric O2 levels

136
Q

Describe the thioglycolate broth of an aerotolerant anaerobe

A

Grows continuous throughout entire tube

137
Q

What are reducing agents?

A

Chemicals that may be added to culture media to reduce oxygen

138
Q

What are examples of reducing agents?

A

Thioglycate, cysteine, H2S, and other sulfur containing compounds

139
Q

What is needed to grow anaerobic microbes?

A

Removal of air and replacement with an inert gas (nitrogen or argon)

140
Q

What are 3 examples of toxic forms of oxygen that can be formed in a cell?

A

1) Superoxide anion (O2-)
2) Hydrogen peroxide (H2O2)
3) Hydroxyl radical (OH●)

141
Q

How is superoxide anion formed?

A

O2 + electron

142
Q

How is hydrogen peroxide formed?

A

O2- + electron + 2 H+

143
Q

How is hydroxyl radical formed?

A

H2O2 + electron + H+

144
Q

What are 4 enzymes that neutralize toxic oxygen species?

A

1) Catalase
2) Peroxidase
3) Superoxide dismutase
4) Superoxide reductase

145
Q

What happens if an obligate anaerobe doesn’t have enzymes to neutralize toxic oxygen species?

A

It can’t combat oxidative stress

146
Q

What is the catalase reaction?

A

H2O2 + H2O2 –> 2 H2O + O2

147
Q

What is the peroxidase reaction?

A

H2O2 + NADH + H+ –> 2 H2O + NAD+

148
Q

What is the superoxide dismutase reaction?

A

O2- + O2- + 2H+ –> H2O2 + O2

149
Q

What is the superoxide reductase reaction?

A

O2- + 2H+ + rubredoxin reduced –> H2O2 + rubredoxin oxidized

150
Q

Define sterilization

A

The killing or removal of all viable organisms (including endospores) within a growth medium

151
Q

Define inhibition

A

Effectively limiting microbial growth

  • No killing
  • Interferes with binary fission, and holds number of bacteria constant so immune system has an easier job
152
Q

Define decontamination

A

Treatment of an object to make it safe to handle

153
Q

Define disinfection

A

Directly targets the removal of all pathogens, not necessarily all microorganisms

154
Q

What is decimal reduction time?

A

Time it takes for a 10 fold reduction in bacterial numbers

155
Q

What is pasteurization?

A

The process of using precisely controlled heat to reduce the microbial load in heat-sensitive liquids
- Does not kill all organisms

156
Q

What is the typical pasteurization for milk?

A

Low-temperature / long-time

-63 C for 30 minutes

157
Q

What is HTST conbination of pasteurization?

A

High-temperature / short-time

- 72 C for 15 seconds

158
Q

What is purpose of pastuerizing milk?

A

Kill Coxiella burnetii, the causative agent of Q fever

159
Q

What is an autoclave?

A

A sealed device that uses steam under pressure

160
Q

In an autoclave, what actually kills the microbes?

A

The high temp, NOT the pressure

161
Q

What is the typical temp/time minimum for an autoclave?

A

The point that takes the longest to hear must stay at 121 C for 15 minutes

162
Q

What are 5 examples of radiation that can reduce microbial growth?

A

1) Microwaves
2) UV
3) X-rays
4) Gamma rays
5) Electrons

163
Q

What does UV have that can cause damage, and what kind of damage can it cause to DNA?

A

Sufficient energy that can cause modifications and breaks in DNA

164
Q

What is useful for in regards to surfaces?

A

Decontaminating surfaces

165
Q

What is generated by electromagnetic radiation that produces ions and other reactive molecules?

A
  • Electrons
  • Hydroxyl radicals
  • Hydride radicals
166
Q

What are 3 sources of radiation?

A

1) Cathode ray tubes
2) X-rays
3) Radioactive nuclides

167
Q

What is radiation used for in the food industry and medical field?

A

Sterilization

168
Q

What can filtration be used as another option for?

A

Heat on sensitive liquids and gases

169
Q

What can be used to accomplish membrane filtration?

A

Syringes, pumps, or vacuums

170
Q

What is needed for filtration to be successful?

A

Pores must be small enough to prevent bacteria from passing through

171
Q

Define bacteriostatic

A

Prevents cell growth as long as the antimicrobial agent is present

172
Q

What are the 3 classifications of antimicrobial agents?

A

1) Bacteriostatic
2) Bacteriocidal
3) Bacteriolytic

173
Q

Define bacteriocidal

A

Kill cells, but does not lyse them

174
Q

Define bacteriolytic

A

Kills and lyses cells

175
Q

What is the minimum inhibitory concentration?

A

The smallest amount of an agent needed to inhibit growth of a microorganism

176
Q

What can cause minimum inhibitory concentration to vary?

A

Organism used, inoculum size, temperature, and pH

177
Q

What is different between the minimum inhibitory concentration (MIC) and the minimum lethal concentration (MLC) and which is usually higher?

A
  • MIC has no growth, but may still have living organisms
  • MLC has no colonies
  • MLC usually higher
178
Q

What kind of media does disc diffusion assay use?

A

Solid

179
Q

Describe a disc diffusion assay

A
  • Antimicrobial agent is added to filter paper disc

- MIC is reached at some distance

180
Q

What is a zone of inhibition?

A

Area of no growth around the disc in a disc diffusion assay

181
Q

Where is disinfectant used?

A

Inanimate objects

182
Q

Where is antiseptic used?

A

Tissue (ex: mouth wash)

Microbio 1010 (8 decks)

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