To calculate the protein concentration using the Bradford Assay, you will need to create a standard curve by plotting the absorbance values against known protein concentrations. Then, using the equation of the best-fit line, you can determine the protein concentration for each tube. Here's how you can do it for Tube 2:
Step 1: Create a standard curve using the absorbance values and known protein concentrations for Tubes 3 to 6.
Tube 3: 2.8 ug protein, Absorbance = 0.144
Tube 4: 5.6 ug protein, Absorbance = 0.256
Tube 5: 8.4 ug protein, Absorbance = 0.361
Tube 6: 11.2 ug protein, Absorbance = 0.464
Step 2: Plot the known protein concentrations (x-axis) against the corresponding absorbance values (y-axis).
Step 3: Find the equation of the line of best fit using a suitable regression analysis, such as linear regression. This equation will be used to determine the protein concentration for Tube 2.
Step 4: Using the absorbance value for Tube 2 (0.068), substitute it into the equation of the line of best fit to calculate the estimated protein concentration.
Note: It is important to have a blank reference measurement (Tube 1) to account for any background absorbance.
Once you have the protein concentration for Tube 2, you can proceed to plot it on the graph along with the other known concentrations.