MBIO 3812 Supplemental Ex McFarland Standard Curve Construction

MBIO 3812 Supplemental Ex McFarland Standard Curve Construction

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MBIO 3812 Supplemental Exercise: McFarland Standards In this exercise you will generate a standard curve of absorbance versus bacterial cell concentration using McFarland Standards. The absorbance of each McFarland standard will be measured in a spectrophotometer and then plotted against the bacterial cell concentration assigned to each standard. As there is a direct/linear relationship between cell numbers and absorbance a straight line should be obtained. The generation of this standard curve will be required for Ex 6-4 Closed-System Growth. Step #1 Read the absorbance of each McFarland standard in the spectrophotometer at a wavelength of 650 nanometers (nm) and record the readings on
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Unformatted text preview: this worksheet . THESE RESULTS MUST BE INCLUDED IN THE BACTERIAL GROWTH CURVE LAB REPORT. Table 1. Calibration Curve with McFarland Standards McFarland Standard # # Bacteria/ml Absorbance 650 nm (raw numbers) Absorbance 650 nm (average) 0.5 1.5 x 10 8 1.0 3.0 x 10 8 2.0 6.0 x 10 8 3.0 9.0 x 10 8 4.0 12.0 x 10 8 Step 2 Construct a standard curve using linear graph paper. Instructions for using Excel to generate the standard curve and obtaining a line of best fit are posted on D2L. Make sure to label the X-axis as the # bacteria/ml and the Y-axis with the absorbance at 650 nm. THIS STANDARD CURVE MUST BE INCLUDED IN THE BACTERIAL GROWTH CURVE LAB REPORT. 1...
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