XXXXXXXXXXTable 1: Standard and Unknown Protein Samples and Their Absorbance BI101 Latest 2014.pdf 57 DETERMINATION OF PROTEIN CONCENTRATION IN MILK PRODUCTS OBJECTIVES 3. Calibrate and use a...

General Biology


Table 1: Standard and Unknown Protein Samples and Their Absorbance BI101 Latest 2014.pdf 57 DETERMINATION OF PROTEIN CONCENTRATION IN MILK PRODUCTS OBJECTIVES 3. Calibrate and use a spectrophotometer. 4. Plot a “standard” curve. 5. Use a standard curve to determine the protein concentration of several milk products. INTRODUCTION qualitative measurement of the presence of proteins. quantitative proteins bind to a dye called Coomassie Blue that is used in the Bradford protein assay. This Determining protein concentration is of importance to biologist studying enzymes. Enzymes are 7 Name___________________________ Lab Section___________________________ 58 Lab Exercise 7 RELEVANCE The ability to precisely measure quantities of nutrients such as proteins is important in quantitatively assess foods enabling us to tailor diets to the needs of patients, the elderly, and your results to nutritional labels. PROCEDURE concentration of protein for each solution, a graph results. This is called a standard curve. spectrophotometer. Micropipette Practice: dispensing volumes from 10-100 I. STANDARD CURVE AND SAMPLE PREPARATION concentration. 1. Mix the tube of Coomassie Blue dye solution by inverting 3-4 times. 2. Next, use the micropipette of 1 mL capacity to add 3 mL of Coomassie Blue dye solution to 9 spectrophotometer cuvettes labeled 0, 1, 2, 3, 4, 5, M1, M2, and M3. L of each protein standard 0, 1, 2, 3, 4, and 5 using the 10-100 L micropipette into the corresponding cuvettes by Be sure to use a fresh tip for each sample. 59 Protein Concentration in Milk Table 1: Standard and Unknown Protein Samples and Their Absorbance Cuvette Label Type of Protein Sample Coomassie Blue Sample Protein Concentration 0 Standard 3 mL 60 L of tube 0 1 Standard 3 mL 60 L of tube 1 2 Satndard 3 mL 60 L of tube 2 3 Standard 3 mL 60 L of tube 3 4 Standard 3 mL 60 L of tube 4 5 Standard 3 mL 60 L of tube 5 M1 3 mL 60 L of tube M1 M2 3 mL 60 L of tube M2 M3 3 mL 60 L of tube M3 M1, M2 and M3 respectively by touching the tip of the pipette to the inside of the cuvette Be sure to use a fresh tip for each sample. 5. vortex each tube so that the mixture produces a uniform color. inaccurate data. II. DETERMINING THE PROTEIN CONCENTRATION OF UNKNOWN SAMPLES 1. Using absorbance data from Table 1, create a standard curve by plotting the absorbance 60 Lab Exercise 7 A bs or ba nc e v al ue s 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Protein concentration (mg/mL) Table 2: Unknown Milk Protein Samples Samples Values Estimated Protein M1 M2 M3 61 Protein Concentration in Milk III. CALCULATIONS Table 3: True Concentrations of Unknown Samples Sample Estimate of Protein Concentration from Multiplied by the Dilution Factor Equals Final Concentration M1 × 50 M2 × 50 M3 × 50 actual composition of the samples if presented nutritional labels from several milk products. Table 4: Converted Concentrations of Unknown Samples Sample Final Concentration Multiplied by the Conversion Factor Equals Concentration M1 × M2 × M3 × 7 g per serving. This value is directly comparable to the provided nutritional labels. Using this 62 Lab Exercise 7 Table 5: Serving-Size Concentrations for the Unknown Samples Sample Concentration Times Number of mL per serving Equals Concentration M1 × M2 × M3 × actual identities to the class. Table 6: Probable Identities of Unknown Samples sample Calculated class average for the Probable milk item Were you M1 M2 M3 IV. QUESTIONS Text1: Text2: Text3: Text4: Text5: Text6: Text7: Text8: Text9: Text11: Text10: Text13: Text12: Text14: Text15: Text16: Text17: Text18: Text19: Text20: Text21: Text23: Text24: Text25: Text26: Text27: Text28: Text29: Text30: Text31: Text32: Text33: Text22: Text34: Text35: Text36: Text37: Text38: Text39: Text40: Text41: Text42: Text43: Text44: Text45: Text46: Text47: Text48: Text49: Text50: Text51: Text52: Text53: Text54: Text55: Name: Lab Section: