Growth & Nutrition Flashcards
1
Q
What are macronutrients?
A
Elements required in large amounts to build macromolecules
2
Q
What are the building blocks of proteins?
A
Amino acids
3
Q
What are the building blocks of lipids?
A
Fatty acids and glycerol
4
Q
What are the building blocks of carbohydrates?
A
Sugars
5
Q
Are sugars polar or nonpolar and what does this mean for their solubility?
A
They are polar and soluble
6
Q
What are the building blocks of nucleic acids?
A
Nucleotides
7
Q
What do inorganic ions often function as?
A
Metabolic co-factors
8
Q
What do enzymes involved in protein synthesis require?
A
K+
9
Q
What do cytochromes (electron carriers) require?
A
Fe2+
10
Q
What does Mg2+ help stabilize?
A
Membranes and nucleic acids
11
Q
What does Ca2+ help stabilize?
A
Cell walls and heat
12
Q
What are micronutrients?
A
Elements required in very small concentrations
13
Q
What are growth factors?
A
Small organic molecules required for growth
14
Q
What are the 3 classes of growth factors?
A
1) Amino acids
2) Purines and pyrimidines
3) Vitamins
15
Q
What is the source of H and O?
A
No specific source, found in H2O and organic media components
16
Q
What is the source of P?
A
Usually provided as phosphate salt (PO4 3-)
17
Q
What is a limiting nutrient?
A
Growth will stop when this nutrient runs out
18
Q
What is the source of inorganic N?
A
Salts (KNO3 or NH4Cl)
19
Q
What must be done to inorganic nitrogen?
A
Must be reduced to NH3
20
Q
What is the source of organic N?
A
Amino acids, which is a nitrogen rich organic molecule
21
Q
What is nitrogen fixation?
A
N2 is reduced to 2NH3
22
Q
What is NH3 used to make?
A
Amino acids
23
Q
Which domains can do nitrogen fixation?
A
Bacteria and archaea
24
Q
What is the source of inorganic S?
A
Salts (MgSO4)
25
What must be done to inorganic S?
Must be reduced to S2-
26
What is the source of organic S?
Amino acids (cysteine and methionine)
27
What kind of carbon do heterotrophs use?
Organic
28
What kind of carbon do autotrophs use?
Inorganic carbon (CO2)
29
What are 6 classes of culture media?
1) Defined medium
2) Minimal medium
3) Complex medium
4) Differential medium
5) Selective medium
6) Enriched medium
30
Describe defined medium
Exact chemical composition is known
31
What is minimal medium?
A defined medium that provides the minimum nutritional requirements for growth (no growth factors)
32
What does minimal medium allow the growth of?
Self-sufficient and "non-picky" microorganisms
33
Describe complex medium
- Exact chemical composition is not known
| - Supply a variety of growth factors
34
What does differential medium allow for?
Different bacteria to be distinguished
35
What does selective medium contain?
Ingredients that inhibit the growth of unwanted microbes
36
What does enriched medium contain?
Special nutrients that encourage the growth of "picky" microorganisms
37
Define metabolism
The sum total of all of the chemical reactions that occur in a cell
38
Define catabolism
Energy-releasing metabolic reaction
39
Define anabolism
Energy-requiring metabolic reactions
40
What are chemorganotrophs?
Microorganisms that get energy from chemical reactions involving organic material
41
What are chemolithotrophs?
Microorganisms that get energy from inorganic chemical reactions
42
What are phototrophs?
Microorganisms that get energy from light
43
What is growth measured as?
An increase in the number of cells
44
What is binary fission?
Cell division following enlargement of a cell to twice its minimum size
45
What is generation time?
Time required for microbial cells to double in number
46
Is there ever mitosis in bacteria and archaea?
No
47
Do bacteria or eukarya have shorter generation times?
Bacteria
48
What is generation time dependent on?
Growth medium and incubation conditions
49
What is exponential growth?
Growth of a microbial population in which cell numbers double at a constant and specific time interval
50
What is the equation to determine final cell number using initial cell number and number of generations?
```
Nt = No * 2^n
(Nt = final cell number; No = initial cell number; n = number of generations)
```
51
What must be plot to produce a linear graph of exponential growth?
The log scale
52
What is microorganism growth limited by?
Amount of nutrients and build-up of waste
53
Is exponential growth limited or unlimited?
Unlimited
54
What is growth rate?
The rate of increase in population number of biomass
55
What is growth rate expressed as for bacteria and archaea?
Number of doublings per hour
56
How can growth rate (k) be calculated?
k = (log Nt - log No) / (0.301 delta t)
57
How is generation time (g) calculated?
g = 1 / k
58
What is batch culture?
A closed-system microbial culture of fixed volume
59
What 4 phases are present in a typical growth curve for the population of cells grown in a closed system?
1) Lag phase
2) Logarithmic / exponential phase
3) Stationary phase
4) Death phase
60
What occurs in the lag phase?
- Growth = death
| - Nutrient-rich and low waste
61
What occurs in the logarithmic / exponential phase?
Growth > death
62
What occurs in the stationary phase?
- Growth = death
| - Nutrient poor and high waste
63
What occurs in the death phase?
Death > growth
64
What is a continuous culture?
An open-system microbial culture of fixed volume (add nutrients and take away waste at same rate)
65
What is a chemostat?
Most common type of continuous culture device
66
What is dilution rate?
The rate at which fresh medium is pumped in and spent medium is pumped out
67
What does concentration of a limiting nutrient control?
Population size and growth rate
68
Describe the Petroff-Hausser counting chamber
Each square corresponds to a calibrated volume
69
What are 3 limitations of microscopic counts?
1) Cannot distinguish between living and dead cells without special stains
2) Small cells can be overlooked
3) Motile cells need to be immobilized
70
What does a cytometer use to enumerate cells in a liquid sample?
Laser beams, flourescent dyes, and electronics
71
What is a viable cell count?
A measurement of only living cells capable of growing to form a population
72
What are the two main ways to perform plate counts?
1) Spread-plate method
| 2) Pour-plate method
73
What is needed to obtain a plate count?
- Preparation and manipulations (dilution tubes, agar plates)
- Incubation time
74
What is the downside to selective culture media?
It only targets particular species
75
Is there a medium that will grow every microbe?
Nope
76
What is the great plate anomaly?
Direct microscopic counts of natural samples reveal far more organisms than those recoverable on plates
77
How is turbidity measured?
A spectrophotometer
78
What is turbidity measured in?
Optical density
79
What happens to absorbance and light transmission as the number of particles increases?
Absorbance increases and light transmission to the photocell decreases
80
Does absorbance distinguish live and dead cells?
Nope
81
What are 3 conditions to make turbidity measurements accurate?
1) Cells must be evenly distributed throughout the medium
2) Cuvette must not have scratches
3) Culture may need to be diluted
82
Define cardinal temperatures
The minimum, optimum, and maximum temperatures at which an organism can grow
83
What occurs at the minimum temperature that an organism can grow?
- Membrane gelling
| - Transport processes so slow that growth cannot occur
84
What occurs at the optimum temperature for an organisms growth?
Enzymatic reaction occurring at maximal possible rate
85
What occurs at the maximum temperature that an organism can grow?
- Protein denaturation
- Collapse of the cytoplasmic membrane
- Thermal lysis
86
What is a psychrophile?
Low growth temperature optimum
87
What is a mesophile?
Midrange growth temperature optimum
88
What is a thermophile?
High growth temperature optimum
89
What is a hyperthermophile?
Very high growth temperature optimum
90
What are 2 examples of mesophiles?
1) Warm blooded animals
| 2) Organisms in terrestrial and aquatic environments
91
What must psychrophiles have to prevent their membrane from gelling?
An outer shell
92
What are psychrotolerant organisms?
Organisms that can grow at 0 C, but have optima of 20 C - 40 C
93
What are 3 molecular adaptations that support psychrophily?
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
What life forms exist above 65 C?
Only prokaryotic
95
Is there phototrophy above 70 C?
No
96
Where are thermophiles typically found?
Terrestrial hot springs
97
Where are hyperthermophiles found?
Boiling hot springs and seafloor hydrothermal vents
98
What are 2 molecular adaptations to support thermophily?
1) Thermal stability for enzymes and proteins
| 2) Cytoplasmic membrane modifications to ensure heat stability
99
What does bacteria have to support thermophily?
Lipids rich in saturated fatty acids
100
What does archaea have to support thermophily?
Lipid monolayer
101
Are enzymes of thermophiles or mesophiles more stable?
Thermophiles
102
What might be the closest descendants of ancient microbes?
Hyperthermophiles
103
What is common to many hyperthermophiles?
Oxidation of H2
104
How does pH affect microbial growth?
Interactions between R groups of amino acids
105
What are neutrophiles?
Organisms that grow best at pH 6 - 8
106
What are acidophiles?
Organisms that grow best at pH
107
What are alkaliphiles?
Organisms that grow best at pH > 9
108
Give 3 reasons why microbial culture media contain buffers.
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
What is water activity?
Water availability
| -The amount of water that is interacting with ions and polar compounds in solution
110
What is water activity expressed in?
A ratio of vapor pressure of air in equilibrium with a substance/solution to the vapor pressure of pure water
111
Between a cytoplasm and the surrounding environment, which typically has a higher [solute] and why?
Cytoplasm because it is small and has a lot of solute per unit volume
112
In what direction does water normally move with respect to a cell and its environment and what does this create?
- Into the cell
| - Creates turgor pressure
113
What are halophiles?
Organisms that grow best at reduced water potential
114
What do halophiles have a specific requirement for?
NaCl
115
Give an example of a halophile
Many marine microbes
116
What are extreme halophiles?
Organisms that require high levels (15 - 30%) of NaCl for growth
117
Give an example of extreme halophiles
Microbes from Great Salt lake or the Dead Sea
118
Define halotolerant
Can tolerate some reduction in water activity of environment, but generally got best at lower solute concentrations
119
Give an example of a halotolerant organism
Staphylococcus aureus
120
What level of NaCl is best for staphylococcus aureus to grow in?
Low
121
What are osmophiles?
Organisms that can grow with high sugar as solute
122
What are xerophiles?
Organisms that can grow in very dry environments
123
What are the 2 rarest categories of organisms?
Osmophiles and xerophiles
124
How do organisms combat low water activity in their surrounding environment?
Increase internal [solute] by
- Pumping inorganic ions into cell
- Synthesizing or concentrating organic solutes
125
What are compatible solutes?
Compounds used by cell to counteract low water activity in surrounding environment
126
Define obligate aerobes
Require oxygen to live
127
Define strict anaerobes
Do not require oxygen and may even be killed by it
128
Define facultative aerobes
Can live with or without oxygen; use oxygen when it is available
129
Define aerotolerant anaerobes
Can tolerate oxygen and grow in its presence but cannot use it
130
Define microaerophiles
Can use oxygen only when it is present at levels reduced from that in air
131
What can be used to distinguish differences in oxygen use/tolerance?
Thioglycolate broth
132
Describe the thioglycolate broth of an obligate aerobe
Grows only in the oxic zone at the top of the tube
133
Describe the thioglycolate broth of a strict anaerobe
Grows only in the anoxic zone at the bottom of the tube
| - Will have majority of growth as far down tube as possible
134
Describe the thioglycolate broth of a facultative aerobe
Grows throughout the tube
| - More growth in oxic zone, steady growth in anoxic zone
135
Describe the thioglycolate broth of a microaerophile
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
Describe the thioglycolate broth of an aerotolerant anaerobe
Grows continuous throughout entire tube
137
What are reducing agents?
Chemicals that may be added to culture media to reduce oxygen
138
What are examples of reducing agents?
Thioglycate, cysteine, H2S, and other sulfur containing compounds
139
What is needed to grow anaerobic microbes?
Removal of air and replacement with an inert gas (nitrogen or argon)
140
What are 3 examples of toxic forms of oxygen that can be formed in a cell?
1) Superoxide anion (O2-)
2) Hydrogen peroxide (H2O2)
3) Hydroxyl radical (OH●)
141
How is superoxide anion formed?
O2 + electron
142
How is hydrogen peroxide formed?
O2- + electron + 2 H+
143
How is hydroxyl radical formed?
H2O2 + electron + H+
144
What are 4 enzymes that neutralize toxic oxygen species?
1) Catalase
2) Peroxidase
3) Superoxide dismutase
4) Superoxide reductase
145
What happens if an obligate anaerobe doesn't have enzymes to neutralize toxic oxygen species?
It can't combat oxidative stress
146
What is the catalase reaction?
H2O2 + H2O2 --> 2 H2O + O2
147
What is the peroxidase reaction?
H2O2 + NADH + H+ --> 2 H2O + NAD+
148
What is the superoxide dismutase reaction?
O2- + O2- + 2H+ --> H2O2 + O2
149
What is the superoxide reductase reaction?
O2- + 2H+ + rubredoxin reduced --> H2O2 + rubredoxin oxidized
150
Define sterilization
The killing or removal of all viable organisms (including endospores) within a growth medium
151
Define inhibition
Effectively limiting microbial growth
- No killing
- Interferes with binary fission, and holds number of bacteria constant so immune system has an easier job
152
Define decontamination
Treatment of an object to make it safe to handle
153
Define disinfection
Directly targets the removal of all pathogens, not necessarily all microorganisms
154
What is decimal reduction time?
Time it takes for a 10 fold reduction in bacterial numbers
155
What is pasteurization?
The process of using precisely controlled heat to reduce the microbial load in heat-sensitive liquids
- Does not kill all organisms
156
What is the typical pasteurization for milk?
Low-temperature / long-time
| -63 C for 30 minutes
157
What is HTST conbination of pasteurization?
High-temperature / short-time
| - 72 C for 15 seconds
158
What is purpose of pastuerizing milk?
Kill Coxiella burnetii, the causative agent of Q fever
159
What is an autoclave?
A sealed device that uses steam under pressure
160
In an autoclave, what actually kills the microbes?
The high temp, NOT the pressure
161
What is the typical temp/time minimum for an autoclave?
The point that takes the longest to hear must stay at 121 C for 15 minutes
162
What are 5 examples of radiation that can reduce microbial growth?
1) Microwaves
2) UV
3) X-rays
4) Gamma rays
5) Electrons
163
What does UV have that can cause damage, and what kind of damage can it cause to DNA?
Sufficient energy that can cause modifications and breaks in DNA
164
What is useful for in regards to surfaces?
Decontaminating surfaces
165
What is generated by electromagnetic radiation that produces ions and other reactive molecules?
- Electrons
- Hydroxyl radicals
- Hydride radicals
166
What are 3 sources of radiation?
1) Cathode ray tubes
2) X-rays
3) Radioactive nuclides
167
What is radiation used for in the food industry and medical field?
Sterilization
168
What can filtration be used as another option for?
Heat on sensitive liquids and gases
169
What can be used to accomplish membrane filtration?
Syringes, pumps, or vacuums
170
What is needed for filtration to be successful?
Pores must be small enough to prevent bacteria from passing through
171
Define bacteriostatic
Prevents cell growth as long as the antimicrobial agent is present
172
What are the 3 classifications of antimicrobial agents?
1) Bacteriostatic
2) Bacteriocidal
3) Bacteriolytic
173
Define bacteriocidal
Kill cells, but does not lyse them
174
Define bacteriolytic
Kills and lyses cells
175
What is the minimum inhibitory concentration?
The smallest amount of an agent needed to inhibit growth of a microorganism
176
What can cause minimum inhibitory concentration to vary?
Organism used, inoculum size, temperature, and pH
177
What is different between the minimum inhibitory concentration (MIC) and the minimum lethal concentration (MLC) and which is usually higher?
- MIC has no growth, but may still have living organisms
- MLC has no colonies
- MLC usually higher
178
What kind of media does disc diffusion assay use?
Solid
179
Describe a disc diffusion assay
- Antimicrobial agent is added to filter paper disc
| - MIC is reached at some distance
180
What is a zone of inhibition?
Area of no growth around the disc in a disc diffusion assay
181
Where is disinfectant used?
Inanimate objects
182
Where is antiseptic used?
Tissue (ex: mouth wash)
