Exam I 2007_Solution - CHE 339/BME 339/BIO 335 Exam I...

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CHE 339/BME 339/BIO 335 Exam I Thursday, October 2, 2007 Your name ________________________________ Part 1: Short Questions: ANSWER IN THE SPACE PROVIDED 1. Name 4 ways for measuring cell growth (4 points). 1) Direct counting (microcope count, particle counting, single cell forward light scattering using flow cytometry, colony forming units) – 1 Point 2) Turbidity measurements – 1 Point 3) Dry cell weight – 1 Point 4) Indirect measurement of cell mass (measure metabolite concentration that is proportional to cell mass or perform a mass balance) – 1 Point 2. In ideal chemostats we assume that the Yield coefficient is constant and independent of the dilution rate but in reality we have to take into account the maintenance energy requirement of the cells. Derive an expression for obtaining the maintenance energy requirement from a set of values of the observed yield coefficient, Yx/s vs the dilution rate D (10 points). 3. Name two key advantages of cell recycle in continuous fermenters ? (6 points). Any 2 of the following 3 – 3 Point each 1) Better substrate utilization 2) Higher X and better productivity 3) More stable to perturbations and washout
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4. Continuous reactors display a higher volumetric productivity than batch reactors, yet they are not as widely used in industry. Name the two major drawbacks of continuous reactors with respect to biotechnology applications (6 points). Higher risk of contamination Higher probability of selecting a mutant with lower productivity 5. Oxygen transfer [16 points total] A. What is the critical dissolved oxygen concentration? (4 points).
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Exam I 2007_Solution - CHE 339/BME 339/BIO 335 Exam I...

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