Chapter 6 - Microbial Growth Flashcards
(114 cards)
1
Q
What is microbial growth?
A
An increase in cell size
2
Q
What is the official name for increased cell size?
A
Hypertrophy
3
Q
What is an increase in cell numbers?
A
Reproduction
4
Q
What is another term for increase in cell number?
A
Hyperplasia
5
Q
What are the two general categories of requirements for cell growth?
A
Physical and chemical factors
6
Q
What is the lowest temperature at which organisms can grow?
A
Minimum growth temperature
7
Q
What is Optimum growth temperature?
A
The temperature at which reproduction is fastest; favorable balance of cell death and reproduction
8
Q
What is the highest temperature an organism can withstand?
A
Maximum growth temperature
9
Q
What are the three physical requirements for growth?
A
Ideal temperature, pH, and osmotic pressure
10
Q
What is the name for cold-loving organisms?
A
Psychrophiles
11
Q
What temperature range do psychrophiles prefer?
A
0 - 20/30 C
12
Q
What is the name of microorganisms that prefer moderate or warm temperatures?
A
Mesophiles
13
Q
What heat range do mesophiles withstand?
A
20 - 40/45 C
14
Q
What is the name of mesophiles that are specifically adapted to human body temperature?
A
Psychrotrophs
15
Q
What is the name of heat-loving microorganisms?
A
Thermophiles
16
Q
What heat range do thermophiles prefer?
A
40 - 80 C
17
Q
If an organism thrives at temperatures above 65 C, what is it called?
A
Extreme thermophile
18
Q
At what temperature do all microorganism die?
A
110 C; proteins denature
19
Q
In what pH range do most bacteria grow?
A
6.5 - 7.5
20
Q
What is the name of organisms that reproduce in an alkaline environment?
A
Alkalophiles
21
Q
What pH do molds and yeasts prefer?
A
5-6 pH
22
Q
What maintains pH homeostasis?
A
Buffers
23
Q
At what pH can very few organisms grow?
A
Less than 4
24
Q
What is the name of organisms that can grow at a pH less than 4?
A
Acidophilic
25
What preserves foods like pickles, sauerkraut, and cheese?
Acids produced during fermentation
26
What is tonicity?
The amount of solutes
27
Same amount of solute within and without
Isotonic
28
More solute outside of cell than within
hypotonic cell in a hypertonic solution
29
If put into a hypertonic solution, what will microbes undergo?
Plasmolysis
30
What 3 steps happen in plasmolysis?
1. water leaves cell
2. cell membrane separates from cell wall
3. death
31
What is the name of organisms that survive in a hypertonic solution?
Halophiles
32
Is the mere presence of water enough to sustain microbial life?
No, water must be present and available
33
What are the three basic chemical requirements of organisms?
1. Carbon
2. Nitrogen
3. Phosphorous and sulfur
34
What makes up 50% of a bacteria's dry weight?
Carbon
35
What is carbon needed for in a cell?
All organic compounds
36
From where can carbon be obtained?
Organic compounds, CO2
37
What percent of a bacteria cell's dry weight is nitrogen?
14
38
What is nitrogen used for in cells?
Nucleic acids, ATP, protein synthesis
39
Where is nitrogen obtained?
Soil, protein catabolism, nitrogen fixation
40
What genus uses nitrogen fixation to obtain nitrogen?
Rhizobium
41
What two elements make up 4% of a bacteria cell's dry weight?
Phosphorous and sulfur
42
What are phosphorous and sulfur used for within a cell?
Nucleic acid synthesis, vitamin production, phospholipid synthesis
43
What is the cell membrane primarily composed of?
Phosphorous and sulfur
44
Where are phosphorous and sulfur obtained from?
Soil
45
If an organism needs oxygen to survive, what is its classification?
Obligate aerobe
46
If an organism requires no oxygen, what is its classification?
Obligate anaerobe
47
If an organism grow better with oxygen but can survive without oxygen, what is it classified as?
Facultative anaerobe
48
What class of organism does not grow in the presence of oxygen, but is not killed by oxygen?
Aerotolerant anaerobe
49
What is a microaerphile?
An organism that needs only a little oxygen to survive
50
What are unstable by-products of aerobic respiration?
Superoxide free radicals (O2-)
51
What do all aerobes produce to break down oxygen?
Superoxide dismutase (SOD)
52
What are the two enzymes that break down peroxide anions?
Catalase and peroxidase
53
What is O2-2?
A peroxide anion
54
What is a hydroxyl radical (OH-)?
A very strong oxidizing agent, by-product of oxygen use
55
What is a highly reactive atom or molecule with unpaired electrons?
Free radicals
56
What is the name of any material prepared for the growth of bacteria in the laboratory?
Growth medium
57
What is a culture?
Microbes that grow an multiply in or on a culture medium
58
What is agar?
A solidifying agent for a culture medium that comes from seaweed
59
What is a chemically defined media?
A media whose exact chemical composition is known
60
What is chemically defined media used to grow?
Fastidious organisms
61
Which media decreases available oxygen?
Reducing media
62
What is reducing media used to grow?
Anaerobic organisms
63
What is complex media?
A media whose exact chemical composition is unknown
64
What is grown on complex media?
Most bacteria and fungi
65
What is the function of selective media?
To inhibit growth of certain organisms and encourage growth of others
66
What kind of media is EMB?
Selective
Eosin Methylene Blue
Inhibit: G+
Select: G-
67
What is Rose media selective for?
G+
68
What is differential media?
It differentiates between different organisms growing on the same plate
69
What allows growth of certain organisms on differential media?
Biochemical reactions
70
What kind of media is Mannitol Salt Agar (MSA)?
Differential - looks for mannitol fermentation
71
What is enriched media?
Media that has additional ingredients in it
72
What kind of organisms are grown on enriched media?
Fastidious organisms
73
What kind of media is a blood agar plate?
Enriched
74
What is incomplete lysis of RBC called?
Alpha hemolysis
75
What is complete lysis of RBC called?
Beta hemolysis
76
What is Gamma Hemolysis?
No lysis of RBC
77
Which media can be used to identify halophiles?
Mannitol Salt Agar
78
Describe the basic composition of mannitol salt agar and what it tests for
- high salt concentration (7.5%)
- inhibits most bacteria
- sugar Mannitol
- pH indicator (phenol red, turns yellow in the acid of mannitol fermentation)
79
What is a colony?
A group of cells of one microbial species
80
What is a pure culture?
One strain of microorganism
81
How are pure cultures usually obtained?
Streak plate
82
What are two methods of preserving bacterial cultures?
Deep-freezing and lyophilization
83
What temperature will deep-freeze an organism?
-50 c to -95 C
84
What is lyophilization?
Deep freezing, dehydrating, then storing an org. in a sealed container; basically powered and can be rehydrated
85
What is bacterial division?
Growth of bacterial cultures
86
What is the primary method of bacterial division?
Binary fission (asexual)
87
What are two methods of bacterial division other than binary fission?
Budding and fragmentation
88
What is a species of organism in one location called?
Population
89
What is the term for the hyperplasia of one species in one location?
Population growth
90
What is another name for cell growth?
Hypertrophy
91
What is the growth rate?
Hyperplasia per unit of time (hour, day, year, etc)
92
What is the time required for the population to double called?
Generation time
93
What is the generation time of bacteria?
20 minutes
94
What kind of equation represents generation time?
Logarithmic
95
What is the equation for generation time?
2^n, n = number of generations
96
What are the four phases of growth?
1. Lag Phase
2. Log Phase
3. Stationary Phase
4. Death Phase
97
In what phase of bacterial growth is the little or no hyperplasia, but lots of metabolic activity?
Lag phase
98
What happens in the log phase of bacterial growth?
Number of new cells greatly surpasses the number of cell deaths
99
What does the length of the log phase depend on?
Environmental availability
100
What is the stationary phase and what causes it?
Cell growth stops due to lack of availability or presence of new inhibitors in environment
101
During which phase are the number of new cells and dying cells equal?
Stationary phase
102
What is the death phase of bacterial growth and what triggers it?
Lack of nutrients or presence of inhibitors causes the number of dying cells to surpass the number of new cells
103
What are the 4 methods of direct measurement of microbial growth?
1. Plate count
2. Filtration
3. Direct Microscopic Count (DMC)
4. Serial Dilutions
104
What does the plate count method count and what assumption is it working off of?
Counts visible colonies of viable microorganisms, assumes each bacterial cell will reproduce enough to form a colony
105
What are the two methods of plate count?
1. Pour plate - put microbe in empty petri dish, pour warm media over
2. Spread plate method - Growth media is solid, inoculate on top
106
How does filtration work to count microbial growth?
Run bacteria through membrane filter with different sized pores that maintain what you want to study
107
What is the disadvantage of DMC?
Organisms can move between squares causing a miscount
108
What is the maximum cell count for a serial dilution?
300 cells
109
In which count of microbial growth is a concentrated sample diluted heavily before inoculation onto a spread plate?
Serial dilution
110
What are the three indirect (guestimate) methods of counting microbial growth?
1. Spectrophotometer - measures light and turbidity
2. Metabolic activity of population
3. Dry weight - used mostly for philamentus orgs. (like mold)
111
What is the scientific name for a relationship between two organisms?
Symbiosis
112
What is a relationship that benefits both organisms?
Mutualism
113
What is a relationship where one organism benefits and the other is neutral?
Commensalism
114
What is parasitism?
One organism benefits, the other suffers
