5_Protein_Analysis_Worksheet_S22

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Jan 9, 2024

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Name: Instructor & Section: Protein Analysis Lab Worksheet Provide a hypothesis regarding the mitochondrial protein quantities in white versus dark meat: (6 points) The dark meat from chicken will be higher in mitochondrial proteins because chickens use their legs more which is where dark meat comes from rather than the upper body (white meat) which is not as active. Bradford Assay Experiment Results Directions 1. Visually compare the color of the unknown sample against the standards of known concentrations. A representative set of standards and a typical color spectrum are shown in Figure 5.3 located in the procedures section of the lab. 2. Using the palette of standards, try to qualitatively determine to which known standard your unknown sample corresponds and estimate the protein concentration in Table 1. Format of your estimation should be “concentration > X < concentration” (2 points) Table 1 Unknown Protein Concentrations Sampl e Estimated Protein Concentration (mg/mL) White Meat Sample (Sample A) 0.25 Dark Meat Sample (Sample B) 0.25 3. Record the standard curve absorbance data from the spectrophotometer report in Table 2. (2 points) Record the absorbance data for the unknown samples (white and dark meat samples) in Table 3. Table 2 Standard Curve Absorbance Values Standard A595 Concentration (mg/mL) 0 BLANK 0.49 0 1 0.65 0.125 2 0.722 0.250 3 0.865 0.500 4 0.964 0.750 5 1.078 1.000 6 1.197 1.500 S22 1
Name: Instructor & Section: Protein Analysis Lab Worksheet 7 1.216 2.000 S22 2
Name: Instructor & Section: Protein Analysis Lab Worksheet 4. Create a standard curve by plotting the A595 (which stands for absorbance at 595 nm) values of the known standards recorded in Table 2 on the y-axis versus the concentrations in mg/mL on the x-axis. Plot the data points on an Excel spreadsheet (scatterplot). Insert a linear trendline and display the equation. (8 points) 0 0.5 1 1.5 2 2.5 0 0.2 0.4 0.6 0.8 1 1.2 1.4 f(x) = 0.35 x + 0.63 Bradford Assay Standard Curve Protein Concentration (mg/ml) Absorbance (nm) Note: A standard curve is a technique of determining the concentration of unknown substances, mainly protein or DNA. Data generated from a set of known samples are used to plot a standard curve by setting the concentration on the x-axis and assay measurement on the y-axis. A straight line shows a linear relationship between data on the x- and y-axes. Data from the sample of unknown concentration will also be plotted the same way. Then concentration of the unknown protein is determined by locating the value on the y-axis that corresponds to the assay value of the unknown protein concentration, following a line to intersect the standard curve. The corresponding value on the x-axis is determined to be the concentration of protein in the unknown sample. During the lab session, you will learn how to generate a standard curve and estimate the concentration of protein in the two meat samples using data generated from the experiment. 5. Calculate the concentration of the unknown sample by plugging the absorbance value of the unknown samples into Y and solving for the corresponding value of concentration (mg/mL) on X. Show your calculations here and record this data in Table 3. (6 points) White meat sample 0.559= 0.3547x+0.6262 0.0672/0.3547 x=0.1894 Dark meat sample 0.563=0.3547x+0.6262 0.0632/0.3547 S22 3
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Name: Instructor & Section: Protein Analysis Lab Worksheet x=0.1781 6. Adjust the final concentration of the unknown samples determined in Step 4 by multiplying the concentration by the dilution factor used. For example, sample diluted 1:50 gives a reading of 0.224 absorbance units, which gives a concentration of M mg/mL (this is an example, not the actual values you are calculating). (2 points) The final concentration of unknown sample is M x 50 = mg/mL . -0.1894(50)=-9.4728 -0.1782(50)=-8.9089 7. Determine the final concentration of the unknown samples and record in Table 3. (4 points) Table 3 Final Concentration of Unknown Samples Sampl e A595 Concentration Read from Standard Curve (mg/mL) Dilution Factor Final Concentrati on (mg/mL) White Meat Sample (Sample A) 0.559 -0.1894 50 -9.4728 Dark Meat Sample (Sample B) 0.563 -0.1782 50 -8.9089 8. Analysis: Discuss this experiment. Was the hypothesis supported? Discuss each step – cell fractionation, spectrophotometry, standard curve, calculation of protein. What were the potential sources of error? Treat this like a lab report analysis. No personal pronouns. (10 points) The hypothesis was possibly supported because there was less mitochondrial protein in the white meat than the dark meat. There was less concentration from the white meat for the standard curve. Might have lost a protein due to a possible contamination in the test which could have affected the results. Or there might not have been enough chicken homogenized in the test. S22 4