1
Q
Method that uses a microscope, special slides, and high-power objective lenses to directly count microbial cells.
A
Microscopic counts
2
Q
Chamber used in microscopic counts that is similar to a hemacytometer.
A
Petroff-Hausser counting chamber
3
Q
Electronic device that scans a fluid as it passes through a tiny pipette to count cells.
A
Coulter counter
4
Q
Device similar to a Coulter counter but can measure cell size and differentiate between live and dead cells.
A
Flow cytometer
5
Q
Method that counts only viable cells because colonies on plates arise from single live cells.
A
Viable plate count
6
Q
Method used when concentrated microbial samples are diluted step by step to reduce their concentration to a manageable level.
A
Serial dilution
7
Q
Technique where diluted samples are plated by either spread plating or pour plating.
A
Colony counting (Viable count)
8
Q
Direct measurement method that counts colonies formed after incubation on agar plates.
A
Viable plate count (Colony counting)
9
Q
Indirect method of microbial measurement using a spectrophotometer.
A
Turbidity
10
Q
Indirect method that measures the activity of metabolic products (like CO₂ or acids) to estimate growth.
A
Metabolic activity
11
Q
Indirect method that measures the weight of microbial biomass after drying.
A
Dry weight
12
Q
What do special stains (serological stains or stains for viable cells) allow in microscopic counting?
A
Differentiation for specific purposes (e.g., live vs. dead cells, specific types of microbes).
13
Q
What range of colony counts is considered statistically valid according to the FDA Bacteriological Analytical Manual?
A
25–250 colonies
14
Q
Formula for calculating CFU per ml in the original sample.
A
Deko ma copypaste sa PPT nalang
15
Q
Enumerate the two main categories of methods for measuring microbial growth.
A
- Direct methods
- Indirect methods
16
Q
Enumerate the direct methods of measuring microbial growth.
A
- Microscopic counts
- Electronic counters (Coulter counter, Flow cytometer)
- Viable plate counts
- Membrane filtration
17
Q
Enumerate the indirect methods of measuring microbial growth.
A
- Turbidity (spectrophotometer)
- Metabolic activity
- Dry weight
18
Q
Enumerate the features of microscopic counts.
A
- Need a microscope, special slides, high power objective lens
- Typically count total numbers, but differential counts are possible
- Difficult for bacteria since they move in/out of the field
- Useful for organisms that can’t be cultured
- Special stains can be used for specific purposes
19
Q
Steps in viable plate count (serial dilution & colony counting).
A
- Prepare concentrated sample
- Perform serial dilution to reduce microbial concentration
- Plate diluted samples using spread plate or pour plate
- Incubate plates
- Count colonies on plates within the valid range (25–250 colonies)
- Calculate CFU/ml using dilution factor and volume plated
20
Q
Enumerate the types of electronic counters.
A
- Coulter counter
- Flow cytometer
21
Q
Statistically valid range of colonies for plate counts according to FDA guidelines.
A
25–250 colonies
22
Q
Formula used when there is more than one plate in the statistically valid range of 25–250 colonies.
A
Ppt nalang
23
Q
In the viable count formula, what does C stand for?
A
Sum of all colonies on all plates between 25–250
24
Q
In the viable count formula, what does n₁ represent?
A
Number of plates counted at dilution 1 (least diluted plate counted)
25
In the viable count formula, what does n₂ represent?
Number of plates counted at dilution 2 (0.1 of dilution 1)
26
In the viable count formula, what does d₁ represent?
Dilution factor of dilution 1
27
In the viable count formula, what does V represent?
Volume plated per plate
28
Method used for samples with low microbial concentration by filtering through a 0.45 µm membrane.
Membrane filtration
29
Typical pore size of membrane filters used in microbiology.
0.45 µm
30
Indirect measurement method where nutrient broth becomes cloudy as microbes grow.
Turbidity (turbidometry)
31
What instrument measures light scattering in turbidometry?
Spectrophotometer
32
In turbidity measurement, what is optical absorbance directly proportional to?
Concentration of bacteria in suspension
33
Turbidity measurement includes both which types of cells?
Live and dead cells
34
Method where cells are removed by centrifugation and weighed.
Mass determination
35
Device used to maintain microbial populations in continuous culture.
Chemostat
36
System where fresh media is continuously added and old broth is removed at the same rate.
Continuous culture
37
Type of microbial cell division where the parent enlarges, duplicates DNA, and splits into two daughter cells.
Binary fission
38
Structure that forms during binary fission to separate the two daughter cells
Septum
39
Type of symbiosis where both partners benefit in an obligatory relationship.
Mutualism
40
Type of symbiosis where one organism benefits while the other is unaffected.
Commensalism
41
Type of symbiosis where one organism benefits at the expense of the host.
Parasitism
42
Association where free-living species compete with each other.
Antagonism
43
Interrelationship between two organisms that benefits them but is not essential for survival.
Synergism
44
Multilayered communities of microbes attached to a surface and each other, often using quorum sensing.
Biofilms
45
Structure developed by biofilms that adheres cells, allows attachment to surfaces, sequesters nutrients, and offers protection.
Extracellular matrix
46
Q: Enumerate the components of the viable cell count formula.
1. C = Sum of all colonies (25–250)
2. n₁ = Number of plates counted at dilution 1
3. n₂ = Number of plates counted at dilution 2 (0.1 of dilution 1)
4. d₁ = Dilution factor of dilution 1
5. V = Volume plated
47
Enumerate the principles of turbidity measurement.
1. Nutrient broth becomes cloudy as microbes grow
2. Turbidity increases with population size
3. Light scattering (diffraction) measured by spectrophotometer
4. Optical absorbance proportional to bacterial concentration
5. Includes both live and dead cells
48
Enumerate the two types of mass determination.
1. Wet mass (cells centrifuged and weighed directly)
2. Dry mass (cells dried then weighed)
49
Enumerate the steps in binary fission.
1. Parent cell enlarges and prepares for division
2. Cell wall, membrane, and volume increase
3. Chromosome duplicates and attaches to membrane site
4. Mid-cell notches form → transverse septum develops
5. Septum grows inward, chromosomes pulled to poles
6. Septum completed, membrane patches → two separate cells
50
Enumerate the types of symbiosis.
1. Mutualism
2. Commensalism
3. Parasitism
51
Q: Enumerate the main features of biofilms
1. Complex relationships among microorganisms
2. Develop extracellular matrix
3. Matrix allows adherence, attachment, nutrient sequestration, protection
4. Form via quorum sensing
5. Microbes often become more harmful in biofilms
52
Defined as an increase in the population of microbes rather than in the size of individual cells.
Microbial growth
53
What is the result of microbial growth that appears as an aggregation of cells arising from a single parent cell?
Discrete Colony
54
Microbial growth is the result of what process?
Reproduction
55
Environmental factors primarily affect what part of microbial physiology?
Function of metabolic enzymes
56
Survival in changing environments depends on whether what systems can adapt?
Enzyme systems
57
Enumerated environmental factors that influence microbial growth.
Temperature, oxygen requirements, pH, electromagnetic radiation, barometric pressure
58
Term used for the acquisition of biomass leading to cell division.
Growth
59
Term for a microorganism’s ability to survive and function under non-optimal conditions.
Tolerance
60
Suffix used to describe conditions permitting growth.
phile
61
Term describing survival without growth under certain conditions.
Tolerant
62
Example organism: grows at high temperatures.
Thermophilic bacterium
63
Example organism: survives high temperatures but grows best at lower ones.
Thermotolerant bacterium
64
Term describing a condition required for growth.
Obligate (strict)
65
Term describing an organism that can grow under a condition but doesn’t require it.
Facultative
66
Atmospheric gases that influence microbial growth.
Oxygen (O₂) and Carbon dioxide (CO₂)
67
Which gas has the greatest impact on microbial growth?
Oxygen (O₂)
68
Oxygen is both an important respiratory gas and a powerful _______.
Oxidizing agent
69
Name the three broad categories of microbes based on oxygen concentration.
1. Use oxygen and detoxify it
2. Cannot use oxygen and cannot detoxify it
3. Do not use oxygen but can detoxify it
70
Extremely reactive oxygen molecule that can oxidize membrane lipids, damaging and destroying cells.
Singlet oxygen (¹O₂)
71
What pigments remove excess energy of singlet oxygen in phototrophs?
Carotenoids
72
Toxic oxygen radical formed during incomplete reduction of oxygen.
Superoxide radical (O₂⁻)
73
Enzyme aerobes produce to detoxify superoxide radicals.
Superoxide dismutase (SOD)
74
Anaerobes die in oxygen due to what reactive molecules?
Superoxide radicals
75
Toxic oxygen product formed during SOD reactions.
Peroxide anion (hydrogen peroxide, H₂O₂)
76
Enzymes used to detoxify hydrogen peroxide.
Catalase or Peroxidase
77
Toxic oxygen product resulting from ionizing radiation and incomplete reduction of H₂O₂.
Hydroxyl radical (OH⁻)
78
Of the four toxic oxygen products, which is the most reactive?
Hydroxyl radical (OH⁻)
79
Which enzymes protect aerobes against hydroxyl radicals?
Catalase and Peroxidase
80
Enzyme that converts superoxide (O₂⁻) into H₂O₂ and O₂.
Superoxide dismutase (SOD)
81
Enzyme that breaks down H₂O₂ into H₂O and O₂.
Catalase
82
Which organisms always have catalase (or peroxidase) and SOD?
Organisms that **can live in or require O₂**
83
Protective enzymes present in bacteria **against oxygen toxicity.**
Catalase and Superoxide dismutase
84
organisms that require O₂ for growth.
Obligate (strict) aerobes
85
organisms that **cannot survive** in O₂.
Obligate (strict) anaerobes
86
Classification: organisms that grow better in O₂ but do not require it.
Facultative anaerobes
87
organisms that tolerate O₂ but **grow better without it**
Aerotolerant anaerobes
88
Classification: organisms that require **low O₂ levels.**
Microaerophiles
89
Oxygen concentration required by strict aerobes.
~20%
90
Oxygen concentration required by microaerophiles.
~2–10%
91
Enumerate the **four toxic forms of oxygen.**
1. Singlet oxygen (¹O₂)
2. Superoxide radical (O₂⁻)
3. Peroxide anion / H₂O₂
4. Hydroxyl radical (OH⁻)
92
Enumerate the three categories of microbes **based on oxygen concentration.**
1. Use oxygen and detoxify it
2. Cannot use oxygen and cannot detoxify it
3. Do not use oxygen but can detoxify it
93
Enumerate the enzyme defenses against toxic oxygen products.
1. Superoxide dismutase → converts O₂⁻ to H₂O₂ and O₂
2. Catalase → converts H₂O₂ to H₂O and O₂
3. Peroxidase → detoxifies H₂O₂
94
Enumerate the classifications of microbes by oxygen requirement.
1. Obligate aerobes
2. Obligate anaerobes
3. Facultative anaerobes
4. Aerotolerant anaerobes
5. Microaerophiles
95
Identify: Require oxygen for growth (~20%).
Strict aerobes
96
Grow in the absence of oxygen; cannot grow in the presence of oxygen.
Strict anaerobes
97
Grow best in the presence of oxygen, but are able to grow (at reduced rates) in the absence of oxygen.
Facultative anaerobes
98
Can grow equally well in the presence or absence of oxygen; can tolerate oxygen but **grow better without oxygen.**
Aerotolerant anaerobes
99
Require reduced concentrations of oxygen (~2–10%) for growth.
Microaerophiles
100
Why is oxygen essential and deadly at the same time
1. Essential for obligate aerobes **(final electron acceptor in ETC).**
2. **Deadly for obligate anaerobes** because toxic forms of oxygen are highly reactive oxidizing agents.
3. **Toxic oxygen causes chain of oxidations** that irreparably damage proteins and lipids.
101
Neither gaseous O2 nor oxygen covalently bound in compounds is poisonous.
What forms are actually toxic?
Highly reactive forms of oxygen (oxidizing agents) like the four types
102
Identify: Organisms that **grow best at a higher CO2 tension** than is normally present in the atmosphere.
Capnophiles
103
Examples of organisms that are capnophiles important in clinical specimens.
1. Neisseria (gonorrhea, meningitis)
2. Brucella (undulant fever)
3. Streptococcus pneumoniae
104
Identify: Why does anabolism often cease in microbes?
Due to **insufficient nitrogen** needed for proteins and nucleotides.
105
Sources of nitrogen for microbial growth?
1. Organic nutrients
2. Inorganic nutrients
3. Recycling nitrogen from amino acids and nucleotides
106
The **reduction of nitrogen gas to ammonia** by certain bacteria that is essential to life on Earth.
Nitrogen fixation
107
Effect of low temperature on lipid-containing membranes?
Membranes become rigid and fragile.
108
Effect of high temperature on lipid-containing membranes.
Membranes become too fluid and cannot contain the cell or organelle.
109
The **three cardinal temperatures** for microbial growth.
1. Minimum temperature
2. Optimum temperature
3. Maximum temperature
110
Temperature below which growth ceases?
Minimum temperature
111
Temperature at which growth rate is fastest.
Optimum temperature
112
Temperature above which growth ceases.
Maximum temperature
113
Time required to reduce microbial population by one log cycle (90%) under specific conditions.
Decimal Reduction Time (D-value)
114
Minimum temperature required to kill a specific microorganism within 10 minutes.
Thermal Death Point (TDP)
115
Enumerate:
Classes of microorganisms by **temperature requirement.**
1. Psychrophiles: 0–15°C optimum, thrive in cold.
2. Psychrotrophs: Grow 0–10°C, optimum 20–30°C, max 35°C.
3. Mesophiles: Optimum 20–45°C.
4. Moderate Thermophiles: Optimum 55–65°C.
5. Extreme Thermophiles (Hyperthermophiles): Optimum 80–113°C.
116
Cold-loving bacteria with **unsaturated fatty acids** in plasma membranes and enzymes **functioning at ~0°C.**
Psychrophiles
117
Identify: Grows at 0°C but **optimum is in mesophile range** (near room temp).
Psychrotroph
118
Midrange temperature organisms, found in warm-blooded animals, soil, aquatic environments.
Mesophiles
119
Mesophiles type that **endure brief exposures to relatively high** temperatures.
Thermoduric organisms
120
Heat-loving bacteria (45–80°C), with **highly saturated membrane** fatty acids and high G+C DNA content.
Thermophiles
121
Organisms with optimum growth >80°C, inhabiting boiling springs and hydrothermal vents.
Extreme thermophiles (Hyperthermophiles)
122
Thermophiles that **grow beyond thermophilic range** and **extend to mesophilic region.**
Facultative Thermophiles (Eurithermophiles)
123
Thermophiles that **do not grow in mesophilic region**, but best at >63°C.
Obligate Thermophiles
124
General pH range for bacterial growth?
pH 6–8
125
Identify: Preferred pH range of fungi.
pH 4–5
126
Organisms that grow best at **low pH.**
Give examples too
Acidophiles
(e.g., *Helicobacter pylori, Thiobacillus thiooxidans*)
127
Organisms that grow best at high pH. Give example.
Alkaliphiles/Alkalinophiles
(e.g., Vibrio cholerae)
128
Organisms that grow best in neutral pH (most pathogenic bacteria).
Neutrophiles
129
Now
Enumerate: pH ranges for microbial growth.
1. Acidophiles: pH 0–5.5
2. Neutrophiles: pH 5.5–8
3. Alkaliphiles: pH 8–11.5
130
How do microbes regulate internal pH despite external extremes?
**By buffers and ion pumps,** maintaining near-neutral internal pH.
131
Organisms that grow optimally between pH 0 and 5.5.
Acidophiles
132
Organisms that grow optimally between pH 5.5 and 8.
Neutrophiles
133
Organisms that grow optimally between pH 8 and 11.5
Alkaliphiles
134
Substances that regulate internal pH of microbes.
Buffers
135
Organisms that require elevated salt concentrations (≥0.2 M) to grow.
Halophiles
136
Example of a halophile that can grow at 1 M or greater salt.
Halobacterium
137
Organisms that can grow over a wide range of salt concentrations.
Osmotolerant (halotolerant) organisms
138
Example of an osmotolerant organism.
Staphylococcus aureus
139
Halophiles that grow in up to 30% salt.
Obligate halophiles
140
Halophiles that **can tolerate** high salt concentrations **but do not require them.**
Facultative halophiles
141
Structures that allow microbes to retain water in dry environments.
Cell walls
142
Structures that cease metabolic activity in dry environments for years.
Endospores and cysts
143
Organisms that live under extreme hydrostatic pressure.
Barophiles
144
The pressure increase for every 10 m depth in water by
1 atm
145
The pressure exerted on a semipermeable membrane by solutes that cannot freely cross.
Osmotic pressure
146
Cell reaction when placed in hypotonic solution.
Cytolysis (swelling and bursting)
147
Cell reaction when placed in hypertonic solution.
Plasmolysis (crenation)
148
Term used for water availability in microbial growth.
Water activity (aw)
149
Formula for water activity.
aw = Psolu / Pwater
150
Organisms that thrive in **high solute concentration.**
Osmophiles
151
Organisms that thrive in high salt concentration.
Halophiles
152
Organisms that tolerate high salt concentration.
Halotolerant
153
Organisms that thrive in high pressure.
Barophiles
154
Organisms that tolerate high pressure.
Barotolerant
155
Organisms that grow in very dry environments.
Xerophiles
156
Obligate halophiles that grow optimally at 25% NaCl but require at least 9%.
*Halobacterium and Halococcus*
157
Facultative halophile that grows in NaCl media ranging 0.1–20%.
Staphylococcus aureus
158
Halophile requiring 1–6% NaCl.
Mild halophile
159
Halophile requiring 6–15% NaCl.
Moderate halophile
160
Halophile requiring 15–30% NaCl.
Extreme halophile
161
Osmophile that thrives in high sugar concentrations.
Saccharomyces cerevisiae
162
Type of culture that is a closed system in broth medium without added nutrients after inoculation
Batch culture
163
General meaning of "growth" in microbiology.
Acquisition of biomass leading to cell division (increase in number of microorganisms).
164
Stage of microbial growth where cells adjust, enlarge, and synthesize but don’t multiply rapidly.
Lag phase
165
Stage of microbial growth where cells divide exponentially by geometric progression.
Logarithmic (exponential) phase
166
Stage where cell division stops, nutrients are depleted, and toxic products accumulate.
Stationary phase
167
Stage where cell death exceeds cell growth.
Death (decline) phase
168
Enumerate the characteristics of death/decline phase.
Cell number decreases due to death
Cell death exceeds cell growth
Viable count decreases
Nutrients depleted, waste accumulates
Environmental conditions become unfavorable
169
Enumerate the characteristics of stationary phase.
Cell division stops due to nutrient depletion and toxic products
Balance between cell division and cell death
Growth rate slows and eventually stops
Viable count remains stationary for some time
Population reaches plateau
170
Enumerate the four distinct stages of batch culture growth.
Lag stage
Logarithmic (exponential) stage
Stationary stage
Death (decline) stage
171
Enumerate the reasons for lag phase growth lag.
Newly inoculated cells require a period of adjustment, enlargement, and synthesis
Cells are not yet multiplying at maximum rate
Population is so sparse/dilute that sampling may miss them
172
Enumerate the two physical effects of water on microbial growth
Osmotic pressure
Hydrostatic pressure
173
The time required for a complete fission cycle, from parent cell to two daughter cells.
Generation time (doubling time)
174
Average bacterial generation time.
30–60 minutes
175
Shortest known bacterial generation time
10–12 minutes
176
Microorganism with a generation time of 10–30 days.
Mycobacterium leprae
177
Bacteria with generation times measured in months.
Environmental bacteria
178
Pathogens with relatively short generation times, causing foodborne illness.
Salmonella enteritidis and Staphylococcus aureus (20–30 minutes)
179
The stage of microbial growth where mean generation time is determined.
Log (exponential) stage
180
Enumerate the **direct methods** of measuring microbial growth.
Microscopic counts
Electronic counters (Coulter counter)
Viable plate counts
Membrane filtration
181
Enumerate the indirect methods of measuring microbial growth.
Turbidity (spectrophotometer)
Metabolic activity
Dry weight
Microbiology
flashcards
Decks in class (22)
# Cards
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Module 6106
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Module 7181
-
Module 8. 1132
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Module 8.2115
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Module 8.3283
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Module 9188
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9191
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11.1191
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11.2170
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Module 11.2160
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Module 12 (Slide 1 To 39)94
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Module 12 (Slide 40 To 65)76
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Module 12 (66-101)156
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Module 12 (-110 Last)25
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LAB EXAM 1 EXERCISES31
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LAB EXAM 1 PPT CULTURE MEDIA107
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Module 13 (VIRUSES)64
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Module Virology Pt.1 (RNA VIRUSES)85
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Module Virology Part 2 (DNA)57
-
Module VIROLOGY Part 3 (Introduction)98
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RNA (Picorna-Coronaviridae)83
-
RNA VIRUS (REO - RHABDOVIRIDAE)49
