Biochemistry Exam
Section B
Answer Question 1 in a separate booklet
Question 1
Answer three (3) of the following five (5) parts. All parts of this question are of equal weight. Use diagrammatic representations to explain and demonstrate the concept that you are referring to, in your answers.
(i) Using an example of a chromatographic separation studied this semester, explain the differences between ‘high resolution separations’ and ‘low resolution separations’, and the phenomenon of ‘band broadening’.
(ii) Describe the two phases used in reversed-phase high performance liquid chromatography, their function in the separation of molecules, and ways in which one can improve the separations obtained.
(iii) How are KD – partition coefficients calculated for the separating solute molecules in partition chromatography and how is this knowledge used in the design of an appropriate chromatographic system?
(iv) Describe the nature of the gel particles used in gel filtration chromatography in terms of their ability to discriminate between the different solute molecules of a sample mixture being chromatographed. Explain the way in which this method may be used as an analytical tool.
(v) Discuss the basis of the separations achieved in affinity chromatography, the design of column particles for this technique, and the methods used in the laboratory to apply this technique to a specific separation.
(20 marks)
Answer Question 2 in a separate booklet
Question 2
Answer three (3) of the following five (5) parts. All parts of this question are of equal weight. Where appropriate, use diagrams to support your answers.
(i) Outline how the body maintains sodium and water homeostasis.
(ii) Case Study: 45 year old female with chronic renal failure
Arterial blood gas
pH 7.28 (7.35-7.45)
PCO2 26 mm Hg (35-45)
PO2 100 mm Hg (80-110)
HCO3 12 mmol/L (23-33)
Plasma
Sodium 135 mmol/L (137-145)
Potassium 5.9 mmol/L (3.1-4.2)
Chloride 101 mmol/L (98-106)
Urea 75.0 mmol/L (3.0-8.0)
Creatinine 0.83 mmol/L (0.05-0.12)
Describe the acid base disturbance
Calculate the anion gap and comment on its significance.
Discuss the interpretation of the plasma results.
(iii) Outline the differences between Type 1 and Type 2 diabetes. Describe the relationship for type 2 diabetes with the metabolic syndrome.
(iv) Using a diagram, show how bilirubin is produced, transported, metabolised and excreted in the body.
(v) Describe and compare the terms “accuracy” and “precision” as used to describe the laboratory results of a biochemical test.
(20 marks)
Answer Question 3 in a separate booklet
Question 3
Answer four (4) of the following six (6) parts. All parts of this question are of equal weight. Where appropriate, use diagrams to support your answers. Please refer to the attached images of the glycolytic and TCA cycles
(i) How is the TCA cycle activity regulated? Explain you answer using the supplied diagram of the TCA pathway.
(ii) Briefly describe the three (3) main reaction steps by which amino acids are degraded in the body.
(iii) One of the important reaction steps in gluconeogenesis is the conversion of pyruvate to phosphoenolpyruvate. Please explain how the cell is able to achieve this considering that it is not possible to reverse the action of pyruvate kinase.
(iv) Uncouplers prevent ATP formation from occurring in intact mitochondria. Please explain why this is so. You can use examples to highlight your answer
(v) Insulin plays a key role in a number of metabolic processes that occur in the body. Briefly describe the effect Insulin has on glucose and fatty acid metabolism in the human body.
(vi) An increase in succinyl CoA formation in the TCA cycle would result in the formation of lactate in a mammalian cell. Please explain how this would take place.