Microbial Growth Flashcards
(134 cards)
1
Q
what does exponential growth mean?
A
the population doubles each division
2
Q
after every generation you see that the population has _____.
A
doubled
3
Q
a cafeteria worker who fails to wash his hands thoroughly and fails to wear his gloves inoculates a quiche with 4 E. Coli cells when he uses his fingers to test whether it is done. by the time you purchase the quiche, there are 128 cells in it. how many generations did the cells go through?
A
5 generations
4
Q
what is the time it takes for a population to double?
A
generation time
5
Q
what is the equation to determine the number of generations?
A
n = (logNt - logN0) / log2
6
Q
what is the equation for growth rate?
A
u = n/t = (logNt - logN0) / (log2 X t)
7
Q
what is the equation for generation time?
A
g = 1/u = t/n
8
Q
define growth rate
A
the number of generations are formed per unit of time
9
Q
what does the generation time formula give you?
A
the time taken for one generation to form
10
Q
which scale is better for graphing the growth rate of a microbial culture? The arithmetic scale or logarithmic scale?
A
the logarithmic scale
11
Q
why is the log scale better for looking at the growth rate of microbial cultures?
A
The log scale makes it easier to read the graph and it has a linear relationship.
12
Q
if a population doubles in 2 hours, what is the generation time for this culture?
A
the generation time is 2 hours
13
Q
what are the 2 phases of growth that are useful?
A
exponential (log) phase and stationary phase
14
Q
when in this phase of growth the bacteria are mostly uniform and are the same age. also, they are making enzymes that are useful and they are dividing uniformly in this phase.
A
exponential (log) phase
15
Q
sometimes we want to keep bacteria in which 2 phases of growth?
A
exponential (log) phase and stationary phase
16
Q
a continuous culture is a ___ culture, which allows you to introduce new nutrients.
A
open culture
17
Q
a continuous culture allows us to continuously maintain bacteria in _____. it allows us to study the ___ of the bacteria in this phase.
A
one phase; physiology
18
Q
what is the method to do a continuous culture?
A
chemostat
19
Q
a continuous culture is continuously adding ____ and removing ____.
A
nutrients; waste products
20
Q
in a continuous culture the cell number does what?
A
remains constant
21
Q
in a continuous culture what is the purpose of the meter pump and the overflow?
A
the meter pump introduces new medium at a constant rate and the overflow takes out nutrients at this rate
22
Q
Biologists like to keep a culture at ____ cells per mL.
A
1 million
23
Q
what are industrial fermenters used for?
A
maintaining cells in a continuous culture. it allows you to check pH, temp, ect. it also allows you to add nutrients as needed.
24
Q
what is an example of a natural fermenter?
A
our digestive system
25
what are the environmental factors that influence bacterial growth?
temperature, pressure, pH, osmotic pressure (salt concentration), oxygen
26
within the ____ temperatures the organism can live, beyond it cannot
cardinal
27
what are the cardinal temperatures?
minimum temp
optimum temp
maximum temp
28
at which cardinal temperatures will bacteria grow the fastest and at which will it grow slower?
it grows the fastest at optimum temperature
| it grows much slower at the minimum and maximum temperatures
29
at what temperature will enzymatic reactions occur at the maximum possible rate
optimum temperature
30
which temperature did you go past if the membrane is gelling and transport processes are so slow that growth cannot occur?
minimum temperature
31
which temperature did you go past if there is protein denaturation, collapse of the cytoplasmic membrane, and thermal lysis?
maximum temperature
32
at high temperatures protein denaturation takes place bc what bonds fall apart?
non covalent bonds
33
below ____ temp the cells are not growing, but are still alive. above ____ temp there is no growth bc the cells are dying.
minimum; maximum
34
proteins need thermal energy to perform enzymatic reactions. this is why enzymatic reactions ____ with increasing temperatures.
increase
35
at a cold temp a cell will have more ___ fatty acids
unsaturated
36
at a hot temp a cell will have more ____ fatty acids.
saturated
37
all the interdomain bonds in a protein are affected by ____.
temperature
38
what type of bonds in a protein are not affected by temp?
covalent bonds such as peptide bonds and disulfide bonds
39
if a protein has too many bonds it will not be very ____.
flexible
40
for a protein at a high temp we want ____ bonds to keep it from denaturing
more (more covalent like disulfide bonds)
41
for a protein at a cold temp we want ____ bonds to keep it more flexible
less
42
what type of bacteria live in normal growth conditions?
mesophiles
43
what is the optimum temperature of mesophiles?
32-37 degrees celsius
44
what is the pH that mesophiles live in?
7.2 - 7.4
45
what is the normal salt concentration of mesophiles?
0.9%
46
most human pathogens are ____
mesophiles
47
what temperatures do psychrotrophs grow between?
0-30 degrees C
48
which bacteria causes food spoilage and can be found in meat, dairy products, and vegetables that are stored at low temperatures?
psychrotrophs
49
which bacteria are sometimes present in probiotics?
psychrotrophs
50
what is the optimum growth temp for psychrophiles?
5 degrees celsius or lower
51
where are psychrophiles found?
polar regions, high altitudes, and the depths of the oceans
52
psychrophiles need their proteins to be more flexible since they are in cold temps. to do this they need ____ inter domain bonds
fewer
53
psychrophiles have more ____ and fatty acids with ____ in their plasma membrane to make it more flexible
unsaturated fatty acids; short chains
54
it is present is psychrophiles. it prevents protein aggregation at low temps. also if proteins aggregate or are misfolded then it can fix them. what is this?
anti-freeze proteins
55
what are the optimum growth temps for thermophiles?
55 degrees celsius or higher
56
where are thermophiles found?
in surface layers of the soils, deserts, compost piles, and hot water heater
57
what are the optimum temps of hyperthermophiles?
100 degrees celsius or higher
58
where do hyperthermophiles grow?
in hot springs
59
what type of bacteria are mostly chemolithotrophs and chemoorganotrophs?
hyperthermophiles
60
what are bacteria that utilize inorganic chemicals?
chemolithotrophs
61
thermophiles need proteins with ____ flexibility. they do this by having ____ inter domain bonds.
less; more
62
in thermophiles plasma membrane they only have ____ fatty acids. they also have lipid ____ and ____ hydrophobic interactions
saturated; monolayers; more
63
thermophiles have ______ proteins
heat shock
64
in thermophiles the lipid monolayer is compose of two polar groups connected by a _____.
biphytanyl
65
in the monolayer of thermophiles the biphytanyl is connected to the polar groups by ____ bonds bc they are more stable at high temps.
ether
66
high pressure can cause bacterial membranes to ____ and proteins to ____.
lyse; denature
67
what organisms are very sensitive to high pressure?
barosensitive organisms
68
what organisms are adapted to grow at very high pressures?
barophiles or piezophiles
69
barophiles can grow up to what pressure?
1,000 atm or 101 MPa or 14,000 psi
70
what organisms grow well over the range of 1-50 MPa, but their growth falls off thereafter?
barotolerant organisms
71
where do barophiles typically live?
the ocean floor
72
many barophiles are also ____ because the average temp at the ocean floor is 2 degrees celsius.
psychrophiles
73
most bacteria grow btw what pH?
6.5-7.5
74
molds and yeasts grow btw what pH?
5-6
75
what bacteria grow in alkaline environments?
alkalophiles
76
some alkalophiles are also ____.
halophiles
77
where can alkalophiles be found?
soda lakes where the salt concentration is high
78
what bacteria grow in acidic environments?
acidophiles
79
where can acidophiles be found?
volcanic soil, sulfur springs (bc of sulfuric acid), and he said our stomach
80
all ____ exhibit optima, minima, and maxima with regard to pH.
enzyme activities
81
changing the pH by as little as how many units can make the enzyme not function?
1 unit
82
____ help us to maintain pH. they do this bc the molecule can accept or donate protons to maintain the same pH.
buffers
83
what molecule in the cell helps us to maintain pH?
amino acids
84
what bacteria grow at pH 5-8 and includes most pathogens?
neutralophiles
85
hypertonic environments, or an increase in salt or sugar, cause _____.
plasmolysis
86
what is the normal solute concentration (isotonic)?
0.85%
87
bacteria cannot survive in a _____ solution bc the cell wall cannot prevent the water from moving out.
hypertonic
88
bacteria are sensitive to ____ salt concentrations
high
89
what type of bacteria require a high osmotic pressure? these bacteria must have a high salt environment to live.
extreme or obligate halophiles
90
to live in these high salt environments, these bacteria have a ______. this gives the cell a high solute concentration which keeps the water inside and not allowing it to move out.
compatible solute
91
what bacteria can tolerate high osmotic pressure? they can grow in low and high salt concentrations.
facultative halophiles
92
many microorganisms use oxygen as a terminal electron acceptor in a process called _____
aerobic respiration
93
what are the toxic forms of oxygen?
superoxide, hydrogen peroxide, hydroxyl radical
94
what enzymes are responsible for detoxifying hydrogen peroxide?
catalase (mostly in cells) and peroxidase (mostly in the bloodstream)
95
what enzyme converts superoxide to hydrogen peroxide?
superoxide dismutase
96
what combination of enzymes converts superoxide into water?
superoxide dismutase/catalase in combination
97
what bacteria grow only in the presence of oxygen, have no fermentation, and perform oxidative phosphorylation?
obligate aerobes
98
do obligate aerobes produce enzymes to detoxify oxygen radicals? if so then what are they?
yes; they produce catalase and superoxide dismutase
99
what bacteria are killed by oxygen, have fermentation, and do not perform oxidative phosphorylation?
obligate anaerobes
100
do obligate anaerobes produce enzymes to detoxify oxygen radicals? if so then what are they?
no, this is why they are killed by oxygen
101
what bacteria grow anaerobically, are not killed by oxygen, have fermentation, and no oxidative phosphorylation?
aerotolerant anaerobes
102
do aerotolerant anaerobes produce enzymes to detoxify oxygen radicals? if so then what are they?
yes; they produce peroxidase/superoxide dismutase
103
what bacteria survive in the presence and in the absence of oxygen, perform oxidative phosphorylation in the presence of oxygen, and perform fermentation in the absence of oxygen?
facultative anaerobes
104
do facultative anaerobes produce enzymes to detoxify oxygen radicals? if so then what are they?
yes; they produce catalase / superoxide dismutase
105
what bacteria grow in low oxygen levels and are killed at high oxygen levels?
microaerophiles
106
do microaerophiles produce enzymes to detoxify oxygen radicals? if so then what are they?
yes; they produce catalase / superoxide dismutase
107
why are microaerophiles killed by high oxygen levels?
they only have low levels of catalase / superoxide dismutase. so they can only detoxify small amounts at a time
108
anaerobic culture methods are ______ media
reducing
109
reducing media that contains chemicals (_______) that combine with ______ to create anaerobic conditions
thioglycolate or oxyrase; oxygen
110
reducing media can be _____ to drive off oxygen.
heated
111
microbes live in ______ and depend on each other to survive. they also ______ with each other.
communities; communicate
112
prokaryotes can respond to the presence of other cells of ______ species.
the same
113
what is the mechanism by which bacteria assess their population density?
quorum sensing
114
what ensures that a sufficient number of cells are present before initiating a response that requires a certain cell density to have an effect?
quorum sensing
115
bacteria have a _____ and once they reach it they will perform a task.
threshold density
116
bacteria produce ______ that let them know when the cell density becomes high.
lipid molecules
117
when the cell density becomes high, the lipid molecules do what to inform the cell of this?
the lipid molecules move back into the cell bc the concentration of the lipid molecules is higher outside of the cell than inside
118
once the cells have been told that cell density is high what do the cells do?
certain gene expressions begin
119
vibrio fischeri exist in a symbiotic relationship with.....
the Hawaiian bobtail squid
120
microbes can live singly or in polysaccharide encased communities termed as?
biofilms
121
biofilms are generally found on _____ surfaces
solid
122
biofilms have _____ through which nutrients and wastes pass.
channels
123
in biofilms, cells communicate by synthesizing ______.
chemical signals
124
in biofilms, clumps of bacteria can _____.
migrate
125
a biofilm can form on any conditioned surface. what is a conditioned surface?
any object that contains a variety of organic molecules
126
in biofilm formation, what does the extracellular polymeric substance (EPS) contain? and where does it come from?
it contains polysaccharides, proteins, DNA, and lipids;
| it comes from cells that are dying off.
127
are biofilms uniform throughout?
no
128
in biofilms, the nutrient concentration is _____ on the outer edges and _____ on the inside.
higher; lower
129
in biofilms, the cells inside will be in ____ phase and the cells on the outer edges will be in ____ phase.
death; log
130
what kind of microbes will you find in the center of biofilms where there is little to no oxygen?
obligate anaerobes
131
the _____ cells maintain the population of the biofilm. the bacteria on the outer edge are exposed to antimicrobial agents, so if they die, the ____ cells can reproduce the population.
persister cells; persister cells
132
why do bacteria form biofilms?
it gives them stability in the growth environment by binding to surfaces and it gives them protection from a wide range of environmental challenges
133
what is bacterial endocarditis?
infection of the heart valves
134
in bacterial endocarditis, the bacteria form a ______ biofilm that protects the bacteria from the host defenses.
fibrin-platelet
