Chapter 4 Flashcards
(142 cards)
1
Q
can be found growing many conditions, including extreme ones:
A
Prokaryotes
2
Q
Prokaryotic cells divide by
A
binary fission
3
Q
population doubles
each division
A
Exponential growth
4
Q
is time it takes for the
population to double in number
A
Generation time
5
Q
how to calculate growth
A
take pic of slide 4
6
Q
number of cells in population at time t
A
N of t
7
Q
initial number of cells
A
N of 0
8
Q
number of generations at that point
A
n
9
Q
pathogen in potato salad at picnic in sun
- Assume 10 cells with 20 minute generation time
- N0 =
- n =
- Nt =
A
- N0 = 10 cells in original population
- n = 12 (3 divisions per hour for 4 hours)
- Nt = N0 x 2n = 10 x 212
- Nt = 10 x 4,096
- Nt =
10
Q
sense changes, adjust to surroundings
A
Cells
11
Q
Most live in polymer-
encased communities
termed
A
biofilms
12
Q
Cause slipperiness of rocks
in stream bed, slimy “gunk”
in sink drains, scum in toilet
bowls, dental plaque
A
biofilms
13
Q
Biofilm formation
A
- Free cells adhere to surface and multiply
- Release polymers to which unrelated cells may attach and grow
- Extra polymeric substances (EPS) give slimy appearance
- Nutrients and wastes pass through characteristic channels
14
Q
Cells communicate by
A
synthesizing chemical signals
15
Q
shields microbes growing within
A
Biofilm structure
16
Q
regularly grow in close association
A
Prokaryotes
17
Q
use type IV secretion system to
inject toxic compounds into competitors
A
Gram negative bacteria
18
Q
defined as population of cells derived from a single cell
A
Pure culture
19
Q
Pure culture obtained using
A
aseptic technique
20
Q
Minimizes potential contamination
A
aseptic technique
21
Q
Contains nutrients dissolved in water
A
culture medium
22
Q
Cells grown on
A
culture medium
23
Q
what can culture medium be
A
broth (liquid) or solid gel
24
Q
Growing Microorganisms on Solid Medium
A
Need culture medium, container, aseptic conditions,
method to separate individual cells
25
what temp agar is sterilized
(Liquid > 95°C; solid < 45°C)
26
Petri dish
plate
27
Simplest plate method, most commonly used method for isolating
Streak-plate method
28
Spreads out cells to separate
Streak-plate method
29
Streak-plate method obtain colonies from
single cells
30
Visible colonies contain how many cells
1 million cells or more
31
Pure cultures maintained as
stock culture
32
Prokaryotes grow on
agar plates
in tubes or
flasks of broth
33
what kind is systems are these: agar plates, in tubes or flasks of broth
closed systems
34
Yields characteristic growth curve
batch cultures
35
another name for closed system
batch cultures
36
Growth curve
37
don't need to know all mediums in slide 38
38
how cells divide in log phase
Cells divide at constant rate
39
what is measured during log phase
generation time
40
which phase is Most sensitive to antibiotics
log phase
41
what does log phase produce
Production of primary metabolites for growth
Secondary metabolites production occurs as nutrients are depleted and wastes accumulate
42
what phase is transferred to new medium
lag phase
43
how do cells increase in lag phase
Number of cells does not increase – no division yet
44
what phase Begin synthesizing enzymes required for growth
lag phase
45
what phase has Nutrient levels too low to sustain growth
Stationary phase
46
how do cells multiply in Stationary phase
•Total numbers remain constant
•Some die; others grow
47
does the secondary phase produce anything
secondary metabolites
48
what happens to cell numbers in Death phase
Total number of viable cells decrease
Cells die at constant rate
49
in what phase does Some fraction may survive at first - Adapted to tolerate worsened conditions.
Phase of prolonged decline
50
number of cells in Phase of prolonged decline
Eventually, most die except a few (survival of the fittest).
51
determines its environment
Position of single cell in colony
52
where in the cell colony has O2, nutrients
the edge
53
has depleted O2 and nutrients, more wastes (potentially toxic)
center
54
Colony may range from exponential growth at what to death phase in what
edges
center
55
another name for open system
continuous culture
56
required to maintain continuous growth
Open system
57
Nutrients added, wastes removed continuously
Open system
58
can maintain continuous growth
chemostats
59
Continually drips fresh medium into culture in chamber
chemostats
60
chemostats maintain cells in what phase
log phase of growth to harvest commercially valuable products
61
extremophiles
live in harsh environments
62
Major conditions that influence growth
Temperature
•Atmosphere
•pH
•Water availability
63
optimum growth : –5° to 15°C
Psychrophiles
64
temp requirements
65
15° to 30°C
•Important in food spoilage
Psychrotrophs
66
25° to 45°C
Mesophiles
67
type of Mesophiles
Pathogens 35° to 40°C
68
45° to 70°C
Thermophiles
69
70° to 110°C
•Usually members of Archaea
•Found in hydrothermal vents
Hyperthermophiles
70
Proteins of thermophiles resist
denaturing
71
slows spoilage by limiting growth
Refrigeration (~4°C)
72
preserves food; not effective at killing microbes
Freezing
73
where is leprosy most common
coolest regions (ears, hands, feet, fingers)
74
growth characteristics: grows only when oxygen is available
use of oxygen: requires oxygen for respiration
protection mechanisms:dismutase and catalase
75
growth characteristics: grows best with oxygen but can without it
use of oxygen: respiration
protection mechanisms: dismutase and catalase
76
growth characteristics: can’t grow with oxygen present
use of oxygen: no use
protection mechanisms: does not dismutase and catalase
77
growth characteristics: grows only if small amount of oxygen is present
use of oxygen: respiration
protection mechanisms: dismutase and catalase
78
y
79
growth characteristics: grows equally well with or without oxygen
use of oxygen: does not use
protection mechanisms: dismutase
80
Harmful by-products of using O2 in aerobic respiration
Reactive oxygen species (ROS)
81
Almost all organisms growing in presence of oxygen produce enzyme
superoxide dismutase
82
Almost all Reactive oxygen species (ROS) produce what
catalase
83
catalase
Convert H2O2 to O2 and H2O
84
Most bacteria maintain constant internal pH, typically near
neutral
85
Pump protons out to
increase pH
86
Pump protons into
decrease pH
87
Range of pH 5 to 8; optimum near pH 7
neutrophiles
88
grow optimally at pH below 5.5
Acidophiles
89
grow optimally at pH above 8.5
Alkaliphiles
90
make water unavailable to cell
Dissolved salts, sugars
91
used to preserve food
Salt, sugar
92
withstand up to 10% salt concentration
Halotolerant
93
require high salt concentrations
Halophiles
94
Major elements examples
carbon, oxygen, hydrogen, nitrogen, sulfur,
phosphorus, potassium, magnesium, calcium, and iron
95
Trace elements examples
cobalt, zinc, copper, molybdenum, mang
96
Component of amino acids, lipids, nucleic acids,
and sugars
Carbon, oxygen, and
hydrogen
97
Component of amino acids and nucleic acids
Nitrogen
98
Component of some amino acids
Sulfur
99
Component of nucleic acids, membrane lipids, and ATP
Phosphorus
100
Required for the functioning of certain enzymes; additional
functions as well
Potassium, magnesium,
and calcium
101
Part of certain enzymes
Iron
102
use organic carbon
Heterotrophs
103
use inorganic carbon as CO2
Autotrophs
104
what is the process of using inorganic carbon as CO2
(carbon fixation)
105
106
N2 to ammonia
Nitrogen fixation
107
Organic molecules that an organism cannot synthesize;
must be present in the environment examples
Amino acids, vitamins, purines, pyrimidines
108
Only grow if these growth factors are available
Amino acids, vitamins, purines, pyrimidines
109
have complicated nutritional
requirements
fastidious
110
Energy sources
Sunlight, chemical compound
111
obtain energy from sunlight
Phototrophs
112
extract energy from chemicals (ex:
Sugars, amino acids, fatty acids)
Chemotrophs
113
inorganic chemicals examples
hydrogen sulfide, hydrogen gas
114
energy from sunlight
carbon from CO2
Photoautotrophs:
115
energy from sunlight
carbon from organic compounds
Photoheterotrophs
116
energy from inorganic compound
carbon from CO2
Chemolithoautotrophs
or
chemoautotrophs,
or
chemolithotrophs
117
energy and carbon from organic compounds
Chemoorganoheterotrophs
or
chemoheterotrophs,
or
chemoorganotrophs
118
contain a variety of ingredients
Complex media
119
examples of Complex media
meat juices, digest, peptones
120
composed of exact amounts of
pure chemicals
Chemically defined media
121
can grow in complex media or chemically defined
media
E. coli
122
inhibit growth of
certain species in a mixed sample
Selective media
123
contain substance that microbes
change in identifiable way
Differential media
124
not selective or differential
Routine medium
125
incubated in air (~20% O2)
Aerobic
126
Require lower O2 concentrations than achieved by
candle jar
Chemical reaction reduces O2 to 5–15%
Microaerophilic
127
obligate anaerobes sensitive to O2
Anaerobic:
127
128
useful if microbe can tolerate brief
O2 exposures
Anaerobic containers
129
provides more stringent approach
Anaerobic chamber
130
used to isolate organism that
constitutes small fraction of mixed population
* Provide conditions promoting growth of particular species
* Relative concentration of target organism increases
Enrichment cultures
131
couting cell total numbers (living plus dead)
Direct cell counts
132
Direct cell counts instruments
Coulter counter, flow cytometer
133
counts only cells capable of multiplying
Can use selective, differential media for particular species
Viable cell counts
134
type of Viable cell counts
Plate counts
135
single cell gives rise to colony
Plate counts
136
number of cells you ideally want in Plate out dilution series
30–300 colonies ideal
137
Plate counts determine
colony-forming units (CFUs)
138
* Concentrates microbes by filtration
* Filter is incubated on appropriate agar medium
Membrane filtration
139
is proportional to concentration of cells
Turbidity
140
how is biomass measured
spectrophotometer
Total weight can be measured
141
only used for filamentous organisms that do not
readily separate into individual cells for valid plate counts
* Cells in liquid culture centrifuged; pellet is weighed
* Dry weight can be determined by heating pellet in oven
Total weight of biomass
