Biochemical Calculations Work Sheet 3 (1).doc

BIOC2181 Fundamentals of Biochemistry BIOCHEMICAL CALCULATIONS WORK SHEET 3 1. You are given a stock solution of 100 mM citrate buffer. How would you dilute it to get 1 ml of 15 mM citrate buffer? 2. How would you m...

BIOC2181 Fundamentals of Biochemistry BIOCHEMICAL CALCULATIONS WORK SHEET 3 1. You are given a stock solution of 100 mM citrate buffer. How would you dilute it to get 1 ml of 15 mM citrate buffer? 2. How would you make 100 μl of 10 mM glucose solution from a 1 M glucose stock solution? (Hint: you might need to do a serial dilution as your pipettes cannot dispense volumes less than 2 μL) 3. What is the concentration of a solution containing 15 mg protein in 250 μl (in mg/ml)? How would you express it as a g/L? 4. How would you make 200 ml of 250 mM phosphate buffer from a 1 M stock solution of phosphate buffer? 5. What amount of casein is there in 5 mL of 0.02 M casein? Give your answer in mmol and µmol. 6. You have a stock solution of haemoglobin. You diluted this 1 in 5, then 1 in 10, and then finally 1 in 2. The final concentration is 0.15 g/100ml. What was the original concentration in g/ml? 7. A microtube is filled with 100 μl of 0.5 M citrate buffer, 60 μl of 2.5 mM p-NPP, 30 μl of acid phosphatase (0.005 mg/ml), and 60 ul of RO water. Ignoring any reaction, what is the final concentration for: (choose the most appropriate units) a. Citrate buffer? b. p-NPP? c. Acid phosphatase? 8. A 14-year-old boy exhibits the following symptoms: fatigue, frequent passage of urine and weight loss. After seeing his general practitioner, he was sent for an oral Glucose Tolerance Test. Blood samples were collected at 30-minute intervals over a total period of 3 hours to measure the levels of glucose in the serum. The serum was diluted x20 prior to the measurement of glucose. In the glucose assay, 50 µl samples of the diluted serum were used. a. The diluted serum prepared from the blood sample collected at 2 hours gave an absorbance measurement of 0.7. Use the standard curve provided at the top of Acknowledgments: Questions 1-7 were created by Stephanie Xu and Beth Caruana and modified by Nirmani Wijenayake  the following page to determine how many nmol of glucose were present in the 50µl sample taken at 2 hours. b. What was the concentration of glucose in the 50 µl sample of diluted serum? (Give units). c. What was the concentration of glucose in the patient’s undiluted serum? (Give units). 1 0.9 Absorbance 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 10 20 30 40 50 60 70 80 90 100 Glucose (nmol) Acknowledgments: Questions 1-7 were created by Stephanie Xu and Beth Caruana and modified by Nirmani Wijenayake