Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
19 Cards in this Set
- Front
- Back
|
What is bacterial growth defined as?
How is it controlled? |
defined as the orderly increase in all major constituents of an organism.
bacterial growth controlled by soap, disinfectants, etc. |
|
|
What is binary fission?
What is the time required for a cell to divide? |
Reproduction of bacteria through one cell growing larger until it becomes 2 cells
Doubling time or generation time |
|
|
Bacteria/E. coli takes BLANK minutes to replicate entire chromosome, BLANK minutes for doubling time, and perform DNA synthesis every BLANK minutes.
|
40, 20, 20
|
|
|
Generation time: g= 0.301(t-to)/(log10N-log10No)
What does N and N0 represent? |
represent cell concentrations at times t and t0
|
|
|
What is bacterial growth defined as? What are 6 ways it is measured?
|
Defined as increases in cell number
1. Counting chamber on microscope. 2. Viable cells measured on agar plates, various methods 3. Filtration, through 0.22 or 0.45 micrometer filters. 4. Turbidimetric methods 5. Mass 6. Growth changes and activity. |
|
|
What is a counting chamber? What is a downside to this growth measurement?
How many microbes needed to be statistically valid? |
Direct microscopic count
problem is that it counts both live and dead cells 10^6 |
|
|
How is mass used as a bacterial growth measurement? Where is it used?
What unit? |
Industrial application involving centrifuged paste
measure the mass in kgs |
|
|
What are the methods of viable plate count?
|
Spread plate, pour plate, and filtration method
|
|
|
Describe the spread plate method
|
Perform a serial dilution by passing 1mL several times. Spread onto an agar plate and count the colonies.
|
|
|
Describe the pour plate method.
What organism is it good for? |
Mix a bacterial sample with moltern agar and pour onto an agar plate. Count the PFUs.
Good for aerobic microbes. |
|
|
Describe the filtration method.
What is it used for? |
guess bacterial load; sample is filtered, put on a plate, and studied.
Used for waste water treatment. |
|
|
How do turbidimetric methods measure bacterial growth?
What is the optimal absorbance? |
Measures bacteria by seeing how it scatters light in a spectrophotometer through absorbance.
A420MM...10^8 CFU/mL |
|
|
How is bacterial growth measured by metabolic activity?
|
By using a sterile probe in a fermentor to measure changes in pH, oxygen uptake, acid development, metabolic product formation.
|
|
|
Describe the continuous method of bacterial growth.
|
Organisms grow in sterile fashion, but new media is added. Process can go on for days/weeks.
|
|
|
What are the four steps involved in a batch culture?
|
Lag phase, exponential phase, stationary phase, and death phase.
|
|
|
What is the phase when microbes are adjusting to a new media environment?
|
Lag phase
|
|
|
What is the phase when the bacterial population is actively growing at a constant rate? When would the bacteria be harvested?
|
Exponential or log phase
Harvest near the end of this phase |
|
|
What is the phase when nutrients are depleting, waste products are accumulating,and growth of microbes plateaus?
|
Stationary phase
|
|
|
What is the phase when nutrients are completed depleted and more cells die than are replaced by new cells?
|
Death phase
|
