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Unformatted text preview: Name (print): Network ID: Signature: Student ID #: MCB 450 EXAM I 3 October 2006 Dr. Mintel Print your name, sign your name, provide your network ID and student ID number at the top of this page and your name at the top of every other page. This exam consists of 10 pages and is a total of 100 points. Your exam booklet will be collected at the conclusion of the examination period. Your grade will be based on the written work contained within the spaces provided. Illegible work will not be considered. You are permitted to use a calculator. No notes of ANY kind are allowed. It is your responsibility to avoid the appearance of cheating and to uphold the integrity of the examination system. DO NOT OPEN THE EXAM BOOKLET UNTIL INSTRUCTED TO DO SO. BEST OF LUCK ON THE EXAM. Multiple-Choice, 3 points each M For each of the following questions, encircle the letter corresponding to the BEST response. 1. Which of the following INCORRECTLY pairs an organelle, or a cell part, with its function? A. Rough end0plasmic reticulum: Synthesis of protein for export B. Mitochondrion : Maj or site for ATP production ' . Ribosome : Site of protein synthesis é Nucleolus : Site of tRNA synthesis E. Nucleus : Repository of genetic information 2. A solution with a pH of 5.0 would have a hydrogen ion concentration of: A. 0.1 M. B. 0.01 M. C. 0.001 M. D. 0.000] M. ® 0.00001 M. 3. The hydrolysis of ATP to ADP and phosphate has a free-energy change of -30.5 klr'mol. The free-energy of hydrolysis of ADP to AMP and phosphate would be expected to have a free-energy change -30.5 kamol. A. greater than ® equal to, or approximately equal to, C. less than 4. Into which functional category should serine and threonine be placed? A. Hydrophobic, nonpolar B. Acidic C. Basic Q) Polar, uncharged Into which fimctional category should aspartate and glutamate be placed? A. Q) C. D. Hydrophobic, nonpolar Acidic Basic Polar, uncharged Secondary structure in a protein is primarily maintained by: A. ® C. D. Van der Waals interactions. hydrogen bonds. ionic interactions. hydrophobic interactions. Which of the following amino acid residues would be most likely to be found in the interior of a globular protein? A 3: (9 D. E. D R L N Q Oleic acid (18:1) would be expected to have a melting point the melting point of stearic acid (18:0). A. C. greater than less than equal to, or approximately equal to Which of the following statements about membranes is INCORRECT? A. ® (2. D. Phospholipids diffuse laterally within a layer, but rarely flip-flop. The phospholipid composition of each of the two bilayers is similar. Transmembrane proteins are frequently decorated with carbohydrate on the exterior side. Phospholipids are oriented in the membrane in a tail—to-tail fashion. 10. What do glucose, galactose, and ribose have in cormnon? A. All are ketoses. B. All are pentoses. C. All are hexoses. ® All are aldoses. i 1. Which of the following cellular components is typically present in bacteria, but absent from most animal cells? A. DNA B. mRN A C. Ribosomes D. Plasma membranes ® Cell wall 12. Which of the following is INCORRECT? A. The four major bases of DNA are adenine, thymine, cytosine, and guanine. Both DNA and RNA have polynucleotide chains containing 3'-5' phosphodiester bonds. Base pairing of the Watson-Crick type occurs in double-stranded B C DNA, tRNA, and rRNA. D. In double stranded DNA, the two strands are itparallel ® DNA with a higher GC content would have a ower melting point than DNA with a lower GC content. 13. The strength of hydrophobic interactions would be expected to be the strength of Van der Waals interactions. 9?) greater than . the same as, or approximately the same as, C. lower than 14. Which of the following is required if someone clones a gene starting from mRNA, but is not required if someone starts with DNA? A. DNA ligase B. Restriction endonucleases C. A cloning vector D. DNA polymerase (9 Reverse transcriptase 15. A plasmid used in cloning, pBR3 22, contains a gene conferring tetracycline resistance (tet’) and one conferring ampicillin resistance (amp’). The ampr gene is opened with a restriction endonuclease and a piece of foreign DNA is inserted. The larger chimeric plasmid is then rescaled with DNA ligase and used to transform heat—shocked E. col 1' cells. What growth characteristics will bacterial cells containing the recombinant plasmid exhibit? A. They will grow on media containing both tetracycline and ampicillin. 0/ '3. They will grow on media containing ampicillin, but not tetracycline. They will grow on media containing tetracycline, but not arnpicillin. They fail to grow on media lacking tetracycline and ampicillin. Short AnswerfEssax Section Point values are given in parentheses after each question number. 16. (6) Assume glycine is present in solution at pH 10.0. Calculate the [-NHZM- NHf] ratio. (pK. = 2.3; pK2 = 9.6) WEQ-SI/l 17. (6) Sketch a curve for the titration of alanine with NaOH starting with alanine in its fillly protonated form. Indicate which regions are in the acid and which are in the basic range. Show which titration corresponds to which group. Put an “X” on the curve corresponding to the isoelectric point. Label the abscissa in terms of the net charge on @MWMWWKW MMMMW (W). 9 M] 8. {5) Calculate a standard free-energy change for the reaction: Glucose + ATP = Glucose 6-phoSphate + ADP using the free energies of hydrolysis in the table below. Compound (Hydrolysis Products) AG" (lemol) ATP ADRPi - Glucose 6-hoshate Glucose, Pi GK) + ATP: Glué>P+HDP “Mo—L lair/M W3”- (14) Define, explain, or characterize briefly: 13) d) g) disaccharide M WA, 2.3, W 65H” “‘5‘” “” 0* aldose etc/W l 0. (4) (a) Make a sketch of a cell membrane containing a transmembrane protein, like glycophorin of erythrocytes. Be sure to label the following structures: the phospholipid bilayer, the transmembrane protein, indicating any important regions of secondary structure, the exterior surface, the interior surface, and any region of the protein that is typically has carbohydrate attached. %WWW' (b) What anchors the protein in the membrane? Explain briefly. 21. (20) Acid hydrolysis of an octapeptide yielded the following amino acids: 2 Ala, Arg, Lys, 2 Asp, Tyr, Gly Treatment of the original octapeptide with trypsin, followed by electrophoresis at pH 6.0 yielded the following products: an arginine—containing tetrapeptide migrating toward the anode a dipeptide migrating toward the cathode a dipeptide remaining near the origin Dansyl chloride (an N-terminal labeling agent) treatment of the original octapeptide, followed by acid hydrolysis, yielded dansyl-Ala. Brief treatment of the original octapeptide with carboxypeptidase yielded Ala. Treatment of the original octapeptide with chymotrypsin yielded two tetrapeptides, both of which remained near the origin upon electrophoresis at pH 6.0. Give a sequence consistent with the foregoing data. Partial credit will be given for each clue that you can correctly interpret. fle-se-m-Mee-flgflmm The End 10 ...
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This note was uploaded on 09/14/2009 for the course MCB 450 taught by Professor Mintel during the Summer '07 term at University of Illinois at Urbana–Champaign.

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FA06Exam1Key - Name (print): Network ID: Signature: Student...

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