2003mcb200f1 - University of Cape Town Department of...

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University of Cape Town Course Code: MCB200F Course Name: Intro to Biochemistry Paper: 1 (Practical) Date: 6 June 2003 No.of pages: 5 Marks: 104 Time: 3 Hours Venue: SC 2 - p.m. ANSWER ALL THE QUESTIONS In the interest of economy please write on both sides of the exam script Please answer each section in a different answer book. Dr J Rodrigues - 45 marks 1. Consider the acid dissociation equilibrium of an amino group: R-NH 3 + R-NH 2 + H + The acid dissociation equilibrium constant is called K a. Suppose the pK a of this particular amino group is 8.5. In a solution at pH 9 (choose the most appropriate answer from those given below): a) there will be more R-NH 3 + than R-NH 2 present in the solution b) there will be more R-NH 2 than R-NH 3 + present in the solution c) the concentrations of R-NH 3 + and R-NH 2 would be equal d) it is impossible to predict the ratio of R-NH 2 to R-NH 3 + with the information given. (1) 2. What is the pH of a solution in which 0.3 mole of acetic acid and 0.6 mole of sodium acetate (Na + CH 3 COO - ) is added (pK a CH 3COOH = 4.0)? (1) 3. Calculate the number of moles of ammonium NH 4 + ions in one litre of a 2 M solution of ammonia at pH 7.2 (pK a = 9.2). (1) 4. If 0.1 mole of free serine and 0.033 mole of serine hydrochloride were dissolved in 1 litre of water, what would the pH of the resulting solution be? (1) 5. 0.1 mL of stock solution is diluted with 2.4 mL H 2 O. Fifty microlitres of this solution is diluted with 0.45 mL H 2 O. The overall dilution is: a) 1:240 b) 1:250 c) 1:400 d) 1:500 (1) 1
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6. Using the data below, construct a standard curve for protein determination. Calculate the concentration of protein in your original cell extract. Please note that 4ml of Buiret Reagent was added in all cases. Marks allocated will be for accuracy and
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This note was uploaded on 01/05/2011 for the course BLY 440 taught by Professor Williams during the Fall '10 term at Alabama.

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2003mcb200f1 - University of Cape Town Department of...

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