9.1, 9.2-9.5, 13.2 Flashcards
1
Q
What is the most common form of bacterial reproduction?
A
Binary Fission
2
Q
What are the 4 steps of Binary Fission?
A
- Growth of cell size and increase in cell components
- Replication of DNA
- Division of cytoplasm (cytokinesis)
- Septum formation and division of daughter cells
3
Q
What is cytokineses direct by?
A
FtsZ protein
4
Q
What assembles to form divisome?
A
FtsZ assembles Z ring to form divisome
5
Q
What does a divisome do?
A
Activates production of peptidoglycan and septum
6
Q
What does is the term called when referring to the time it takes to double population?
A
Generation Time (Doubling Time)
7
Q
How long is the generation time for E. Coli?
A
20 minutes
8
Q
How long is the generation time for B. subtilis?
A
120 minutes
9
Q
What is the generation time for S. Aureus?
A
30 minutes
10
Q
What is the generation time for M. Tuberculosis?
A
15-20 hours
11
Q
What is this equation used for?
Nn= N02^n
A
Calculating the population size
12
Q
What does the Nn represent in Nn= N02^n?
A
Number of cells at generation n
13
Q
What does N0 represent in Nn= N02^n?
A
Initial number of cells
14
Q
What does ^n represent in Nn= N02^n?
A
number of generations
15
Q
What is culture density?
A
of cells/unit vol.
16
Q
Which step of the growth curve has the inoculum cells added and adjust to culture medium; no change in population?
A
1st step: Lag phase
17
Q
Which step of the growth curve has binary fission occurring; cell replication > cell death
A
2nd step: Log (exponential) phase
18
Q
Which step of the growth curve has resources becoming depleted; cell replication = cell death
A
Step 3: Stationary phase
19
Q
Which step of the growth curve has endospores forming; cell replication < cell death
A
Step 4: Death Phase
20
Q
What occurs during Lag phase?
A
- Cells grows larger; metabolically active
- Damaged or shocked cells undergo repair
- Initial cell numbers do not change
21
Q
What are some factors that determines the duration of the lag phase?
A
Genetic make-up
Media composition
Initial inoculum size
22
Q
How is generation time determined?
A
Genetically determined; intrinsic growth rate
23
Q
_____ vs____ is exponential
A
Time vs # of cells is exponential
24
Q
At what point of the growth curve are the microbes most susceptible to disinfectants and antibiotics that affect protein, DNA, and cell-wall synthesis?
A
Log (exponential phase)
- this is because they are more focused in growing/expanding rather than repairing
25
What happens during log phase?
Constant growth and uniform metabolism
26
What happens during stationary phase?
Waste accumulates; nutrients gradually used up
Culture density is constant
Undergo sporulation
27
At which point of the growth curve do cells’ synthesis slows; less susceptible to antibiotics; expression of virulence factors and secondary metabolites?
Stationary phase
28
At which phase of the growth curve has toxic waste accumulating; nutrients exhausted
Death Phase
29
Why and when do cells lyse and release nutrients
During death phase; to help surviving cells and endospore-formers
30
What are surviving cells with slow metabolism called? What are some characteristics of them?
Persisters
Chronic infections (tuberculosis) and antibiotic resistance
31
What type of system culture has infinite resources; nutrients and air are replenished; dead cells and waste are removed? What is an example of this system?
Open system cultures
Chemostat
32
What method of quantifying populations size has cells counted under a microscope?
Direct microscopic cell count
33
What is a flaw when using direct microscopic cell count?
It cannot distinguish live vs dead
34
When using the direct microscopic cell count method, what is the calibrated slide where we put our known volume called?
Petroff-Hausser chamber
35
What method of quantifying populations size has cells counted under a microscope or flow cytometer and has a red stain bind to damage cells for indication?
Fluorescence Staining
36
What method of quantifying population size detects electrical resistance change due to cell density (as fluid that contains particles/cells is drawn through the micro-channels, each particle causes a brief change to the electrical resistance of the liquid?
Coulter counter
37
Is there a flaw when using Coulter counter?
Yes, it doesn’t differentiate live/dead
38
What method of quantifying populations size is a count of viable cells; samples are diluted and grown on solid media
Viable Plate counts
39
How are the results of viable plate counts expressed?
Colony forming units per volume (CFU/ml)
40
What is the countable range in a viable plate count? What is it when it’s TFTC and TNTC?
30-300 CFU/ml
<30 - TFTC (too few to count)
>300 - TNTC (too numerous to count)
41
What method is used to measure growth when the sample is very dilute and may not contain enough microbes for plate count?
Membrane filtration technique
42
What does the membrane filtration technique do?
Known vol. filtered through a membrane; membrane plated and colonies counted
43
What does most probable number (MPN) mean?
Statistical method used when counts are very low ( <30 CFU/ml)
44
What happens during the method of MPN?
Uses 3 log dilutions grown in 3-5 replicates
Growth is determined positive or negative
Pattern is compared to reference table
45
What is turbidity?
optical density (describes a material’s ability to absorb the power of a given light)
46
What is turbidity measured with?
Spectrophotometer
47
What happens within a spectrophotometer?
Light is passed thru culture and measured on other side
48
turbidity increase = ?
Population increase
49
What microbe divides asymmetrically (budding)?
Planctomycetes: Gemmata obscuriglobus
50
What microbe divides via fragmentation?
Cyanobacteria
51
What is secreted by organisms in the biofilm?
EPS- extracellular polymeric substances
52
What is EPS (extracellular polymeric substances)?
Hydrated polysaccharide gel with other macromolecules and channels
53
How is biofilm formed?
Through quorum sensing (cell to cell communication)
54
Quorum sensing can cause what?
Cell density or cellular stress
55
What is it called when small molecules are produced to induce various actions?
Autoinducer
56
What autoinducer class are found in gram -
N-acylated homoserine lactones
57
What autoinducer class are found in gram +
Various short peptides
58
What is an example of beneficial biofilm?
Normal biota in lungs
59
What is an example of harmful biota?
Plaque formation on teeth
60
How does biofilms provide resistance to antibiotics?
- Cells in deep laters may be metabolically inactive
- EPS may slow diffusion of biocidal agents
- Provide optimal environment for sharing of plasmids
61
What main factors affect growth?
Oxygen level, pH, temp, osmotic pressure, barometric pressure
62
What’s a low percentage agar tube that has a gradient of oxygen called?
Fluid Thioglycolate Medium (FTM)
63
What is determined by location of growth in a FTM?
Aerotolerance
64
If growth is found more on the top of the FTM, what is it labeled as based on their oxygen requirement?
Obligate aerobes
65
If growth is found more at the very bottom of the FTM, what is it labeled as based on their oxygen requirement?
Obligate anaerobes
66
If growth is found mainly on the top, but also scattered throughout the FTM, what is it labeled as based on their oxygen requirement?
Facultative anaerobes
67
If growth is found throughout the FTM randomly, what is it labeled as based on their oxygen requirement?
Aerotolerant anaerobes
68
If growth is found almost at the top of the FTM, what is it labeled as based on their oxygen requirement?
Microaerophiles
69
Which macromolecule is most vulnerable to the changes of pH
Proteins
70
What are fermenters mostly adapted to regarding to pH?
Acidity
71
What range of pH are neutrophils at?
~7
72
What range of pH are acidophiles at?
pH<5.5
73
What range of pH are alkaliphiles at?
pH 8-10.5
74
What temp are mesophiles usually found in?
20-45 C
75
What temp are psychotrophs found in?
4-20 C
76
What temp are Psychrophiles found in?
<0 C
77
What temp are thermophiles found in?
50-80 C
78
What temp are hyperthermophiles found in?
80-110; some survive @ >121 C
79
What are salt/solute lovers called and where are they usually found?
Halophiles; oceans
80
What are high salt tolerators called and where are they found?
Halotolerant; salt marshes where high solutes aren’t present all the time
81
What does barometric pressure mean?
Ability to withstand great pressure
82
What are barophiles?
Microbes that require high atmospheric pressure
83
Where are barophiles found?
Bottom of ocean
84
Because Barophiles could be found in the bottom of the ocean, what type of temp microbes could they be?
Thermo or hyperthermophiles
85
What are cyanobacteria and green sulfurs classified as?
Photoautotrophs
86
What are purple nonsulfurs classified as?
Photoheterotrophs
87
What does PAR stand for and what light spectrum are they usually within?
photosynthetically active radiation; visible light spectrum (400-700nm)
88
What is the oldest and most common form of physical means of control of microbes?
Heat sterilization
89
What does heat sterilization do?
Alters membranes and/or denatures proteins
90
What is “lowest temp that will kill in 10 min” called?
Thermal Death Point
91
What is “length of time to kill at a certain temperature” called?
Thermal Death Time
92
At what temperature des dry heat occur?
> 250C
93
What is it called when there is direct application of high heat; also known as incineration?
Dry Heat
94
What is called when there is an application of high temperature liquid/vapor?
Moist heat
95
What makes moist heat more beneficial than dry heat?
Moist heat penetrates cells better than dry
96
At what temperature and pressure does an autoclave have to reach?
~121C and 15 psi
97
What are the 2 types of autoclaves and how does it work?
Gravity-uses steam to push out air
Prevacuum- vacuums out air first
98
T/F Autoclaves require periodic quality controls (QC) to check for functionality
True, autoclave tape, spore tests, Diack tubes, and recorders are used for QC
99
What type of Heat sterilization semi-sterilizes the food but does not ruin food quality?
Pasteurization
100
What temperature and time does HTST pasteurization need?
Milk is heated at 72C for 15 seconds
101
At what temperature and time does UHT pasteurization need?
138 C for 2 or more seconds
102
What 8 milk borne organisms are killed by pasteurization?
Campylobacter jejuni, Coxiella burnetii, Listeria monocytogenes, E. Coli O157:H7, Mycobacterium tuberculosis, M. Paratuberculosis, Salmonella spp., Yersinia enterocolitica
103
T/F Refrigeration and freezing are usually not for static, but sterlization
F, it’s usually used for static which means it slows metabolism but will grow when temps are raised
104
What is pascalization?
High pressure used in food industry to kill microbes
105
What is desiccation?
Drying or dehydration
106
What method of sterilization is used for millennia to preserve foods like raisins, prunes, jerky, etc.
Desiccation
107
What is it called when using freeze-drying; rapid freezing then placed under vacumn?
Lypophilization
108
Salts or sugars in jams are helpful for desiccation sterilization because they lower _______?
Water activity of foods/materials without physical drying
109
What is ionizing radiation?
Radiation that enters into the cells and disrupts molecular structures such as DNA
110
T/F ionizing radiation can be used to sterilize non-autoclavable items
True
111
What doesn’t penetrate through glass, plastics, etc. but can damage cells w/ direct exposure
Non-ionizing radiation
112
What is UV irradiation?
Forms thymine dimers in DNA causing lethal mutations
113
What are high frequency sound waves that disrupt cell structure and causes bubbles to form inside cells and induce lysis?
Sonication
114
What is the use of barrier to physically separate microbes?
Filtration
115
What does membrane filtration do?
Removes microbes from liquid samples
116
How is air commonly filtered?
Through high-efficiency particulate air (HEPA) filters
117
What is the correct order of the steps of biofilm formation?
1. Production of extracellular polymeric substance (EPS)
2. Attachment of planktonic cells to a substrate
3. Attachment becomes irreversible; cells become sessile
4. Growth and division on substrate
5. Attachment of secondary colonizers and dispersion of microbes to new locations
2, 3, 4, 1, 5
