Exam1-05 - Multiple Choice Questions 1. The purity of an...

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Multiple Choice Questions 1. The purity of an enzyme at various stages of purification is best measured by: a. Total protein b. Total enzyme activity c. Specific activity of the enzyme d. Percent recovery of protein e. Percent recovery of the enzyme 2. Which would be best to separate a protein that binds strongly to its substrate? a. Gel filtration b. Affinity chromatography c. Cation exchange d. Anion exchange e. Cation or anion exchange 3. How many hydrogen bonds can a water molecule potentially take in liquid form? a. one b. two c. three d. four e. none of the above 4. How does the hydrophobic effect influence the structures of large molecules? a. Nonpolar molecules are not easily solubilized in water and aggregate b. Polar groups are oriented on the surface, interacting with the water c. Nonpolar molecules can mask the polar characteristics of the hydrophilic molecules d. a) and b) e. a) and c) 5. The most important buffering system for maintaining proper blood pH is: a. the charges on the amino acids b. the bicarbonate buffer system of CO 2 , carbonic acid, and bicarbonate c. phosphate groups of serum phosphoproteins d. none of the above e. all of the above 6. Myoglobin binding of oxygen depends on: a. the oxygen concentration (pO 2 ) b. the hemoglobin concentration c. the affinity of myoglobin for the O 2 (K) d. a) and c) e. a), b) and c)
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7. In the α helix the hydrogen bonds: a. are roughly parallel to the axis of the helix b. are roughly perpendicular to the axis of the helix c. occur mainly between electronegative atoms of the R groups d. occur only between some of the amino acids of the helix e. occur only near the amino and carboxyl termini of the helix 8. In the binding of oxygen to myoglobin, the relationship between the concentration of oxygen and the fraction of binding sites occupied can best be described as: a. hyperbolic b. linear with a negative slope c. linear with a positive slope d. random e. sigmoidal 9. Which of the following is true about the properties of aqueous solutions? a. A pH change from 5.0 to 6.0 reflects an increase in the hydroxide ion concentration ([OH - ]) of 20%. b. A pH change from 8.0 to 6.0 reflects a decrease in the proton concentration ([H + ]) by a factor of 100. c. Charged molecules are generally insoluble in water. d. Hydrogen bonds form readily in aqueous solutions. e. The pH can be calculated by adding 7 to the value of the pOH. 10 The Henderson-Hasselbalch equation: a. allows the graphic determination of the molecular weight of a weak acid from its pH alone. b. does not explain the behavior of di- or tri-basic weak acids c. employs the same value for pK a for all weak acids d. is equally useful with solutions of acetic acid and hydrochloric acid e. relates the pH of a solution to the pK a and the concentrations of acid and conjugate base 11. Two amino acids of the standard 20 contain sulfur atoms. They are: a. cysteine and serine b. cysteine and threonine c. methionine and cysteine d. methionine and serine e. threonine and serine
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12. An octapeptide composed of four repeating glycylalanyl units has:
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This note was uploaded on 10/17/2011 for the course CHEM 653 taught by Professor Wei, robert during the Spring '11 term at Cleveland State.

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Exam1-05 - Multiple Choice Questions 1. The purity of an...

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