Microbial Growth And Control (Lec 6-7) Flashcards
1
Q
Bacterial Growth
A
Increasing the # of cells
2
Q
Binary Fission
A
Cell division following enlargement of cell to 2x it’s normal size
3
Q
Generation Time
A
Time it takes to double cell population
4
Q
Peptidoglycan Biosynthesis
A
Production of new cell wall material
5
Q
Cocci cell wall synthesis
A
Wall grows in opposite directions outward of the FtsZ ring
6
Q
Rod-shaped cell wall biosynthesis
A
Wall grows at several points along the cell
7
Q
Autolysins
A
Creates small openings in the wall which new cell material is added across
8
Q
Bactoprenol
A
C55 alcohol that is large enough to transport sugar peptidoglycan across the cell membrane
9
Q
Glycolase
A
- Enzyme that interacts with bactoprenol to insert cell wall precursors into the growing points
- Catalyzes glycosidic bond formation
10
Q
Transpeptidation
A
- Final step in cell wall synthesis
- Forms peptide cross-links between glycan chains
- Inhibited by antibiotic penicillin
11
Q
Peptidoglycan elongation
A
MreB organizes the elongasome
12
Q
MreB
A
- forms simple cytoskeleton bands around the cell under the membrane in bacteria and probably archaea
- directs cell wall synthesis to specific points along the rod-shaped cell
13
Q
Elongasome
A
Protein that helps elongate/form the rod shape of some bacterias
14
Q
Divisome
A
- Squeezes and divides cell at FtsZ ring during division
15
Q
FtsZ Ring
A
- Forms ring around center of cell the divisome can build from
- location determined by Min Proteins
- DNA replicates before ring forms
- related to tublulin (a protein responsible for cell structure and microtubules)
16
Q
Exponential Growth
A
- growth starts slow and becomes faster
- growth of microbial population where cell numbers double in a specific time
- N = No2^n
N = final # No = initial # n = generation #
17
Q
Batch Culture
A
- Closed-system of microbial culture with fixed volume
- Lag phase, Exponential phase, Stationary phase, Death phase
18
Q
Lag phase
A
- To keep culture from dying keep in this phase of NO GROWTH
- freeze or dehydrate colony
- Time between inoculation of culture and beginning of growth
19
Q
Why do Cells have to Die?
A
2nd Thermo law: energy becomes more disorganized
20
Q
Exponential phase
A
Cells in this phase are typically healthiest
21
Q
Stationary Phase
A
Cell population growth is zero
22
Q
Death phase
A
If incubation continues after stationary phase the cells will die
23
Q
Continuous Culture
A
- Open-system of microbial culture of fixed volume
- Chemostat: most common device
-Controls growth rate by dilution rate
-Controls growth yield by concentration of limiting nutrient
24
Q
Growth Rate
A
How much colony grows determined by dilution rate: (rate which new growth medium pumped in and spent out)
25
Growth Yield
Population density (cell # / mL) controlled by limiting nutrient.
26
Cytometer
-counts cells in liquid samples
-uses lasers, fluorescent dyes, and electronics
27
Viable Cell Counts
-Measures living, reproducing cell population
-Use serial dilutions to make plate counts
-Can be unreliable bc growth medium is good for some bacteria and bad for others
28
Spectrophotometry
- measures turbidity through light absorption called Optical Density (OD)
- standard curve must be established
- sometimes clumps of biofilms formed by microbes can be problematic
29
Cardinal Temperatures
- Min, max, and optimum temperatures for an organism
- classifies organisms into psychrophile, mesophile, thermophile, and hyperthermophile
30
Pyschrophile
Low temp loving
-More flexible a-helices than B-sheets
-High unsaturated fatty acid content
-More polar and strong bonds
31
Mesophile
Midrange temp loving
32
Thermophile
High temp loving
-critical amino acid substitutions in a few locations provide heat-tolerant folds
- increased # of ionic bonds between basic and acidic amino acids
- produces solutes that stabilize proteins
- bacteria: lipids rich in saturated fatty acids
- archaea: lipid monolayer not bilayer
33
Hyperthermophile
Extremly high temp loving
-Produces enzymes widely used in industrial microbiology
-Ex Taq polymerase automates polymerase chain rxn technique
34
Osmolarity effect on growth
- Usually, cytoplasm solute concentration is higher than surroundings so water moves in
- If low water activity/high solute [ ] of surroundings cell water moves out or pumps solute in
35
Halophiles
Grow best with NaCl and reduced water
36
Extreme Halophiles
Require high level of NaCl to grow (15-30%)
37
Halotolerant
Can tolerate lower water activity, however best in absence of added solute
38
Osmophiles
Grow best in high sugar environments
39
Xerophiles
Grow in very dry environments
40
Compatible solutes
Neutral solutes that can help organisms survive extreme osmotic stress
41
Aerobes
Require Oxygen to live
42
Anaerobes
Do not require/can be killed by Oxygen
- lots of human pathogens anaerobic
43
Facultative aerobes
Can live with or without Oxygen
44
Aerotolerant anaerobes
Can grow in Oxygen environments but don't use it
45
Microaerophiles
Use oxygen when it is present at levels reduced from that in air
46
Thioglycolate Broth
Medium that separates microbes based on Oxygen requirements
47
Reducing agents
Chemicals added to culture media to reduce Oxygen
48
Heat Sterilization
Most common method of controlling microbial growth
49
Pasteurization
Uses precisely controlled heat to reduce microbes in heat-sensitive liquids (does not kill all organisms)
50
Microwave Radiation
Energy from waves hits and damages cells
51
UV Radiation
Shorter wavelength higher Energy but penetrates surfaces less
52
Filtration
Avoids heat on sensitive liquids/gases however only stops bacteria, not viruses
53
Bacteriostatic
-Inhibits growth/no killing
-best for medicine because immune system kills all strains not just those selected for high resistance
54
Bacteriocidal
- Kills cells without lysing
- If used in medicine will select for resistance
55
Bacteriolytic
- Kills cells with lysing
- If used in medicine will select for resistance
56
Minimum inhibitory concentration (MIC)
- Smallest amount of an agent needed to inhibit growth
- Specific to each organism
- Double [] each test tube when figuring out capacity
