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