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16 Cards in this Set

  • Front
  • Back
Bacterial growth refers to cell size, not numbers. T or F?
False: refers to cell numbers
The bacterial curve is based on bacteria growing in a ______ system
closed
Explain the lag phase
1. Just innoculated
2. Increase in size, NOT num
3. Length depends on mediums used and how health cells are and temp
Explain the exponential phase.
1. Bacteria divide
2. Increase and double
3. It is constant and balanced with NO lag
Explain the stationary phase.
1. Growth tapers off
2. Growth rate = death rate
3. Cell die and release nutrients for others to use
4. Starvation phase may occur
Explain the death phase
1. Reverse of the growth phase
2. Too much waste
3. Not enough nutrients
4. Viable, but not culturable cells present
Explain survival
1. Those left at the end
2. Endospores
3. Mutated organisms
4. MAY end up with viable bacteria that can be re-cultured
Why is this survival aspect significant
Because basically, we don't really know if we are killing off all of the bacteria.
Why do we care about the measurement of growth?
For research, and heath standards (food, milk, water)
What are the 6 different types of population counts?
1. Colony Counts
2. Turbidity
3. Dry Weight Analysis
4. Chemical Analysis
5. Statistical Estimation
6. Actual or Direct Microscopic Counts
Explain Colony Counts
Based on the idea that each bacteria gives rise to a colony. We use the dilution method to cound CFU's
Explain Turbidity
Uses visual standards or a spectrophotometer to measure optical density
Explain dry weight analysis
Counts live and dead organisms
Explain chemical analysis
Measures DNA and protein in just a single cell - then can determine the rest of the population
Explain statistical estimation
Uses tests which have a predetermined range of numbers of bacteria for specific results
Counts only live bacteria
Explain actual or direct counts
Using stains and grid lines...then multiply