CH 369 - Multiple Choice Questions (3 points each) 1. The...

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1 Multiple Choice Questions (3 points each) 1. The sequence of Drosophila calnexin was recently determined by screening a cDNA library, and it is thought that this protein is bound to the membrane of the ER. Which segment of the following protein sequence would most likely be inserted into the membrane? a. Cys-Ser-Phe-Asp-Ile-Lys-Arg-Arg-Tyr-Ile-Asp b. Arg-Glu-Ser-Asp-Ser-Phe-Val-Asn-Lys-Val-Cys c. Ile-Trp-Gly-Ile-Gly-Leu-Val-Ala-Ile-Val d. Val-Glu-Leu-Ala-Lys-Ala-Asn-Pro-Ser 2. The ɛ amino group of lysine has a pK a of 10.8. What percentage of the groups will be unprotonated (i.e. are –NH 2 rather than NH 3 + ) in a dilute solution of lysine at pH 7.0? a. 20% b. 50% c. 70% d. 80% e. Less than 10% 3. 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. 4. What factor(s) limit(s) the conformation of the protein backbone? a. double-bond character of the C-N bond b. steric strain limitations c. hydrogen-bonding interactions d. a. and b. e. a., b., and c.
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2 5. In the β -pleated sheet conformation,: a. there are hydrogen bonds perpendicular to the direction of the polypeptide chain. b. the polypeptide chain is more extended than in an α helix. c. the polypeptide chains may be hydrogen bonded together in a parallel or antiparallel orientation. d. both a. and c. e. a., b., and c. 6. 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. 7. Myoglobin and the subunits of hemoglobin have: a. no obvious structural relationship. b. very different primary and tertiary structures. c. very similar primary and tertiary structures. d. very similar primary structures, but different tertiary structures. e. very similar tertiary structures, but different primary structures. 8. Which of the following structures is adenine? 9. What net charge will the following pentapeptide possess at neutral pH? Ser-Phe-Glu-Arg-Asn a. 3+ b. 2_ c. 1+ d. 0
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3 e. 2- 10. Choose the best match of the amino acids in the left column with the appropriate side chain types in the right hand column. A = Lys
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This note was uploaded on 06/07/2011 for the course CH 369 taught by Professor Kbrowning during the Spring '07 term at University of Texas.

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CH 369 - Multiple Choice Questions (3 points each) 1. The...

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