Term
| What kind of slide do we use for direct count? |
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Definition
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Term
| What kind of dye did we use for direct count? |
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Definition
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Term
| What are the two reasons why we use direct count? |
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Definition
1. To quantify # of bacteria/ bacteria [conc.]
2. To count blood cells |
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Term
| What is the equation for the cell concentration? |
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Definition
[cells]= average # of cells x 2 =
4x10-6ml |
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Term
| Where did the 2 come from in the cell concentration equation? |
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Definition
The D.F. of
100ul bacteria
100ul bacteria + 100ul methylene blue
= 1/200= 1/2= "2" |
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Term
| Whatr are the four methods to quantification? |
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Definition
- Direct count
- Plate count
- Filtration
- Turbidimetry
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Term
| What is the labeled axis of the turbidity graph? |
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Definition
| Optical density [y] vs. Bacteria ml [x] |
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Term
| What are the limitations of quantification method? |
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Definition
- Cannot distinguish live vs. Dead cells
- Generlizing a STD curve
- Must dilute bacteria [conc] if it is too high
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Term
| Turbidity graph and g time equation |
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Definition
Bacteria/ Time
Gtime= Tf -Ti
3.3 log (nf)
ni |
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Term
| What does Live/dead stain? |
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Definition
| Stain for bacterial viability |
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Term
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Definition
| When light wave strike a fluorescence molecule the atom becomes excited and it moves to an unstable energy state. The atom will fall back to its normal energy state while releasing a light energy photon |
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Term
| What are the two types of dyes used on Live/Dead? |
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Definition
1. STYO9 green nucleic acid stain
2. Propidum Iodide red fluorecent nucleic acid stain |
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Term
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Definition
| Stains all living cells and dead cells |
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Term
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Definition
| Stains cell with damaged membranes |
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Term
| What are the limitations with STYO9 and propidum iodide dyes? |
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Definition
- Dead cells with intact membrane will stain Green.
- Live cells with damage membrane will stain Red
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Term
| What are the limitations of Direct count? |
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Definition
| Cannot distinguish live vs. Dead cells |
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Term
| For Turbidity what machine do we use to measure? |
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Definition
| The spectometer to measure the cell [conc] of the OD (Optical density) |
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Term
| how does a spectrophotometer work? |
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Definition
| measure how much light pass through it |
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Term
| what are the advantages and disadvantages of turbidimetry and filtration? |
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Definition
- can count the concentrated samples
disadvantage:
live and dead cells cannot be differentiated |
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Term
| what is fluorescent/ how does it work? |
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Definition
| when light wave strike a fluorescence molecule the atom becomes excited and it moves to an unstable energy state. The atom will fall back to its normal energy state while releasing a light energy photon. |
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