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14 Cards in this Set
- Front
- Back
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Asexual process of this lab |
The asexual process of growth that will be measured in this is binary fission, where the daughter cells will predictably increase in mass till they each reach maturity & undergo binary fission as well. |
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At a cellular level, define bacterial growth |
-an increase in the number & size of the organelles, the cytoplasm volume, and the amount of cell wall and cytoplasmic membranes. |
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Direct Physical Measurment |
the volume of cells (by dry weight, or wet weight) |
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Direct chemical measurment |
-the contents of the cells ( total protein, total DNA content) can also be measured and reflect the amount of growth. |
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Indirect measurement of chemical activity of cells |
-(such as the rate a gas is produced or consumed) will also reflect growth but the size of the cell (new daughter cell versus mature cell) can affect the results. |
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Indirect Turbidity Measurments |
-use a instrument to measure the amount of light that is scattered as it passes through a tube of nutrient broth and cells, called a spectrophotometer. |
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Turbidity or optical density (cloudy) |
-its directly related to the cell mass or cell number. Any particulate in the liquid media will block the light. |
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Exponential Growth |
-a rate of growth really only seen with bacteria & not capable with other microorganisms. |
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Lag Phase |
-begins immediately after the sterile nutrient inoculated with bacterial cells. |
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Exponential (Logarithmic) Phase |
-a "regular pattern" of binary fission and cell growth such that the population of bacteria is doubled at a constant rate. This is the generation time, and is also known as the doubling time. |
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Stationary (Plateau) Phase |
-occurs at there are limitations on the amount of time growth conditions are optimal. At this point the number of cells growing and dividing equals the number of cells dying. Spores begin to form. |
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Death Phase |
-is where the number of viable cells decreases exponentially. Because a "dead" cell and a spore can still block light like the "live" cell, turbidity measurements cannot detect this phase. |
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Plate Counts |
-can also be done (a long with the serial dilution) technique to estimate the number of bacteria per mL. Colony Forming Units, the ideal number of CFU's is in the range of 30 to 300. |
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Must know how to do line graph & its math. |
Draw two different dot lines where the growth is going up rapidly the most. Called the exponential phase. The bottom line must be exactly half of the top. Then subject the high line from the low. |
