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18 Cards in this Set
- Front
- Back
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Bacteria divide by?
Describe? |
binary fission
copy DNA + split into two |
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Two pathways that function during bacterial cell cycle?
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DNA replication & partition
cytokenesis |
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4 Stages of microorganism growth and descriptions?
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Lag-Bacteria preparing to multiply;preparing enzymes, etc.
Exponential(log)-Rapid growth phase. Cells exhibit most typical biochemical rxns & morphology. Stationary-Cells dying same rate as generated Death-Nutrients depleted,waste building up. Irreversable loss of ability to reproduce. |
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Define unbalanced growth
What phases of growth would you observe. |
rates of synthesis of cell components vary
stationary or death stages |
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Starvation response
Define/Describe |
Entry into stationary phase d/t starvation or other stressful conditions.
Morphological changes endospore formation <size,nucleoid condensation,DNA shrinkage means no replication. |
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Two hypotheses for death phase
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cells are viable but not culturable-capable of growth if conditions improve
programmed cell death-fraction of the population genetically programmed to die. |
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Why do we use a logarithmic scale for measuring microbial growth?
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The log scale tends to straighten lines-easier to interpret graphs
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+/-
counting chambers |
easy,inexpensive,quick
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flow cytometry |
specific antibodies can be used to determine size/internal complexity
counts dead cells as well as live |
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+/-
mbn filters |
cells stained with dyes
can distinguish living from dead cells |
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pour plate +/-
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good for liquid loving orgs
possible to kill your orgs by too hot of agar hard to count in 3D |
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spread plate +/-
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Easier to count in 2D
Don't have to worry about killing orgs with hot agar |
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Cell counting expressed in which units?
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CFUs-colony forming units
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If microbe cannot be cultured on plate media what is another viable counting method?
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Turbidometric measures
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Two scales in turbidity measures?
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% transmittance
absorbance |
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+/-
dry weight |
time consuming
not very sensitive |
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+/- Quantity of particular cell constituent
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useful if amt. of substance in each cell is constant
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this device is used to study continuous growth-
how does it work? |
chemostat
continuous provision of nutrients cont. removal of wastes |
