Microbial Growth - Chapter 3 Flashcards
(126 cards)
1
Q
How do eukaryotic cells replicate?
A
Through meiosis and mitosis
2
Q
Binary Fission Steps
A
Replicate DNA, cell elongation, cell separation
3
Q
Cell Elongation
A
Formation of division septum, where 2 cells separate
4
Q
What is made at the septum?
A
Cell membrane, cell wall, capsule
5
Q
Cell Separation
A
How mitochondria divide
6
Q
FtsZ Ring
A
Protein that forms a ring, tells the cell where to build layers so that it can separate -> will get smaller and smaller, and eventually the 2 layers will separate themselves
7
Q
Cytokinesis
A
Septum formation is faster and simpler to replicate bacteria compared to mitosis
8
Q
What is fragmentation common in?
A
Bacteria that form filaments
9
Q
Fragmentation
A
Break into 2 pieces which expand to a longer filament, not very common, not just limited to bacteria
10
Q
Budding
A
How yeast divide, asymmetric division -> big and little cell form
11
Q
Bacterial Counts Formula
A
Nn = N0 x 2n
12
Q
Nn
A
Total bacteria after n replications
13
Q
N0
A
Starting number of bacteria
14
Q
2n
A
n is the number of replications, can calculate by doing the time passed divided by the doubling time
15
Q
Doubling Time of E. coli
A
20 minutes
16
Q
Doubling Time of M. tuberculosis
A
15-20 hours
17
Q
Doubling Time of M. leprae
A
14 days
18
Q
Bacteria Growth Curve
A
Lag phase, log phase, stationary phase, death phase
19
Q
Lag Phase
A
Gearing up for replication as they have a good amount of nutrients, cell size increases, increased metabolism, and protein production
20
Q
Lag Phase Line
A
Straight as the bacteria count doesn’t change
21
Q
Log Phase
A
Exponential growth, actively dividing, most susceptible to antibiotics and disinfectants
22
Q
Log Phase Line
A
Line going up
23
Q
What can antibiotics target?
A
DNA, RNA, or protein synthesis
24
Q
Stationary Phase
A
Run out of nutrients and oxygen, build-up of waste, rate of division is equal to the rate of death, bacteria go into survival mode
25
Survival Mode for Bacteria
Sporulation starts, slow growth, produces metabolites that are released
26
Stationary Phase Line
Straight line
27
Death Phase
Increase of toxic waste that's killing them, no nutrients left, bacteria undergo lysis to make nutrients for other bacteria to survive, spores are released, persister cells
28
Persister Cells
Cells that refuse to die, tend to have antibiotic resistance
29
What tends to have antibiotics?
Plasmids
30
Direct Methods to Count Bacteria
Petroff-Hausser Chamber/Coulter Counter
31
Indirect Methods to Count Bacteria
Plate count (CFU), most probably number, optical density, measure dry weight, measure ATP (cell viability)
32
Direct Counting of Bacteria
Zoom in on one slide of the cell and count the cells in that square, can make a dilution to help count, not very common
33
CFU (Plate Count)
Colony-forming units, using a dilution to approximate the amount of bacteria
34
CFU Process
Have a stock solution and make serial dilutions, from each dilution plate a portion and spread it to find individual colonies (want 30-300), count colonies in the plate then plug into a formula to get the total bacteria
35
What does each colony start as?
1 bacteria
36
Is CFU accurate?
It may be inaccurate as there are a lot of steps and we have the bacteria grow in between our stock culture and counting
37
Optical Density
Uses a spectrophotometer to measure turbidity in bacteria
38
Turbidity
Cloudiness
39
Spectrophotometer
Measure turbidity in bacteria and will get a specific absorbance as the light bounces off of the bacteria
40
What blank is used in the spectrophotometer for optical density?
A TSB media as the same media needs to be used in the blank and the samples
41
Why is optical light density indirect?
It doesn't give an actual amount of bacteria, but rather the cloudiness of the solution
42
How can bacteria grow?
Freely grow or attach to a surface to grow
43
Planktonic
Free-floating
44
Sessile
Attach to a surface
45
What growth do bacteria need to be to live in a community?
Need to be sessile
46
How do bacteria talk to each other?
Through quorum sensing
47
Quorum Sensing
Coordination of activities in response to environmental stimuli
48
What does quorum sensing occur between?
Microbes of the same or different species
49
Autoinducers
Small chemicals that the bacteria release that interact with cells
50
Gram-Positive Bacteria Autoinducers
Short peptide
51
Gram-Negative Bacteria Autoinducers
N-acetylated homoserine lactone
52
What needs to be done to make a community/biofilm?
The bacteria release autoinducers and must reach a threshold to make bacteria
53
What are the steps of biofilm formation?
-Reversible attachment of planktonic cells
-First colonizers become irreversibly attached
-Growth and cell division
-Production of EPS and formation of water channels
-Attachment of secondary colonizers and dispersion of microbes to new sites
54
When there are enough bacteria what do they secrete (2nd step)?
They secrete a matrix which holds them together
55
Extrapolymeric Substance
EPS, holds things together, semipermeable substance, and communities are normally antibiotic resistant
56
How do we get rid of the biofilm?
We have to disrupt the biofilm to get rid of it since it is antibiotic-resistant
57
Why is there attachment of secondary colonizers and dispersion of microbes to new sites?
The bacteria will run out of nutrients and room
58
Where do biofilms commonly form?
In water systems or on catheters
59
What is one of the only extreme places bacteria can't grow in?
Volcanoes
60
What does thioglycolate medium do?
It sucks the oxygen out of the bottom of the media
61
Obligate Aerobes
Require oxygen, growth on the top
62
Obligate Anaerobes
Dislike oxygen, growth on the bottom
63
Facultative Anaerobes
Prefers oxygen but can grow without it, the majority of growth on the top
64
Aerotolerant Anaerobes
Indifferent to oxygen, equal growth throughout
65
Microaerophiles
Like oxygen but not at the level of atmospheric oxygen, growth close to the top
66
Capnophiles
Like carbon dioxide, dislike oxygen
67
Where do capnophiles grow best?
Candle jars
68
Candle Jar
Candle consumes oxygen providing the preferred environment
69
Capnophiles Examples
Haemophilus sp. and Campylobacter jejuni
70
What does Haemophilus sp. cause?
Influenza-like disease
71
Where does Campylobacter jejuni live?
In the intestines
72
Acid
Low pH
73
Base
High pH
74
Neutral
Middle pH, ~7
75
Acidophile
Like acidic pH's, 1-5.5
76
Neutrophile
Like neutral pH's, 5.5-8.5
77
Alkaliphile
Like basic pH's, 7.5-11.5
78
Acidic Environments
Vagina and stomach
79
Examples of acidophiles
Sulfolobus sp. and Lactobacillus sp.
80
Examples of neutrophiles
E. coli and Salmonella sp.
81
Examples of alkaliphiles
Vibrio cholera and Natronbacterium sp. (can survive the highest pH)
82
Is it easier for bacteria to survive low or high pHs?
Low pHs as it is easier to pump out hydrogen ions
83
Acidic - H or OH?
H
84
Basic - H or OH?
OH
85
pH effects on DNA
High pH breaks hydrogen bonds as the OH groups take the hydrogens
86
pH effects on lipids
High pH hydrolyzes (breaks down) lipids
87
pH effects on proteins
Slight changes in pH make a big difference (denature)
Changing ionization -> unfolding/misfolding -> degradation
88
What is proton motive force also known as?
Electron transport
89
High pH effects on proton motive force
At a high pH H binds to OH to form water instead of a gradient
90
Low pH effects on proton motive force
At a low pH you need energy to pump H out to the high H environment, against the gradient causing a gradient problem
91
Electron Transport
Pump H ions across the membrane and bring them back to make ATP
92
What changes do acidophiles make to adapt to a changing pH?
Proteins have negatively charged surfaces, hydrogen efflux pumps, change the lipid composition of the plasma membrane to withstand low pH (modify lipids)
93
What changes do alkaliphiles make to adapt to a changing pH?
Modified lipid and protein structures and modified proton motive force
94
How do acidophiles make the protein have negatively charged surfaces?
They bring in positively charged particles
95
Efflux Pump
Gets rid of hydrogen ions, takes energy
96
What are the changes in ions in alkaliphiles?
The molecules used for electron transport may be changed to keep the gradient such as Na instead of H to prevent the formation of water.
97
What temperature do psychrophiles like?
Cold temperatures around 10 degrees C
98
What temperature do mesophiles like?
Temperatures around 37 degrees C
99
What temperature do thermophiles like?
Temperatures around 65 degrees C
100
What temperature do hyperthermophiles like?
Temperatures around 95 degrees C
101
Psychrotolerant Temperatures
Can survive in the cold but prefer warmer temperatures, 3-35 degrees C
102
Optimal Temperature of Psychrophiles
15 degrees C, but can survive below 0 degrees C
103
At what temperature do psychrophiles die?
20 degrees C
104
Where do psychrophiles live?
Cold lakes and the ocean floor
105
Mesophiles Optimal Temperature
Moderate, around 20-40 degrees C
106
Mesophile Examples
E. coli, Salmonella sp., and Lactobacillus sp.
107
Where are thermophiles found?
Hot springs, geothermal soil, or compost
108
Thermophiles Examples
Thermus aquaticus and Geobacillus sp.
109
Where are thermophiles found?
Hydrothermal vents
110
Hyperthermophiles Examples
Pyrobolus sp. and Pyrodictium sp. (can survive the autoclave)
111
What are the effects of low temperatures on macromolecules?
Membranes slow down and lose fluidity, chemical reactions slow down, and diffusion slows down
112
What are the effects of high temperatures on macromolecules?
Membrane lipids speed up which disrupts metabolic processes, proteins and nucleic acids will denature
113
Psychrophiles Bonds
Decrease in secondary stabilizing bonds
114
Hyperthermophiles Bonds
Increase in G-T content in DNA and increased secondary bonds in proteins
115
Psychrophiles Flexibility
Proteins are highly hydrophobic due to increased flexibility
116
Hyperthermophiles Saturation
Increase saturated/polysaccharide lipids to limit membrane fluidity
117
Hyperthermophiles Amino Acid Usage
Alter amino acid usage to prevent protein denaturing
118
Isotonic
No net movement of water, equal solutes
119
Hypertonic
Higher concentration outside the cell, shrivel, water moves outside the cell
120
Hypotonic
Higher concentration inside the cell, burst/lyse, water moves inside
121
Halotolerant
High salt isn't ideal, but it can grow
122
Nonhalophile
Don't like salt, isotonic environment, like 0.5% concentrations of salt
123
Halophiles
Love salt, found in salt lakes and oceans, increased glycerol (prevents shrinking as water can't move as well) and efflux pumps
124
Barophiles
Need high atmospheric pressure for growth, found at the bottom of the ocean
125
Photoautotrophs
Use light energy and CO2 is the primary carbon source
126
Photoheterotrophs
Use light energy, but can't use Co2 as a sole carbon source, use organic moelcules as their main carbon source
