10.09 - Examination I - Name: _ 1 General Biochemistry Exam...

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1 General Biochemistry Exam I Tuesday, October 9 th , 2007 4:00 – 6:00 PM ! Put your name and identification number on the answer sheet. ! Mark only one answer for each question on the answer sheet. ! Use only the pencil provided for the examination. ! Do not fold or bend the answer sheet. ! Make sure you have 13 question pages. ! Read each question carefully. 1. List atoms commonly found in proteins that can act as hydrogen-bond donors when linked to hydrogen. (1) carbon (2) oxygen (3) nitrogen A. 1 only B. 2 only C. 3 only D. 2 and 3 E. 1 and 3 F. 1 and 2 G. 1,2,3. 2. Which of the following post-translational modifications converts a side chain that is neutral at pH 7 to one that is negatively charged? A. hydroxylation of lysine B. carboxylation of glutamate C. acetylation of lysine D. phosphorylation of threonine Name: ____________________
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2 For questions 3-7 . Choose the correct answer from the list below. A. glutamic acid B. methionine C. histidine D. tyrosine E. proline F. glycine G. arginine 3. ____________ This amino acid residue can only be found on the N-terminus of an ! helix because when it is part of a polypetide it does not have an alpha N-H for hydrogen bond formation. 4. ____________ The amino acid with R group that can best act as buffer at pH 7. 5. ____________ This amino acid has a side chain that is usually negatively charged at pH 7. 6.____________ This amino acid is recognized by trypsin. 7.____________ This amino acid has the smallest side chain and highest conformational flexibility. 8. Why is the peptide bond planar? A. The presence of disulfide bonds prevents rotation. B. The charges on some of the side chains limit movement. C. It contains partial double-bond character, preventing rotation. D. None of the above. E. All of the above. 9. Which of the following amino acid residues would most likely be buried in the interior of a water soluble, globular protein? A. Asp B. Ser C. Asn D. Ile E. Glu 10. What is the advantage of adding SDS to gel electrophoresis? A. SDS allows proteins to be separated on the basis of approximate mass. B. SDS reduces disulfide bonds. C. SDS allows proteins to be separated on the basis of their pI. D. None of the above. E. All of the above.
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3 11. Two-dimensional electrophoresis is a combination of what two techniques? A. Isoelectric focusing and affinity chromatography. B. Isoelectric focusing and SDS-PAGE. C. Affinity chromatography and SDS-PAGE. D. Ion-exchange chromatography and SDS-PAGE. E. Isoelectric focusing and ion-exchange chromatography. For questions 12-17 . Choose from the following list. A) coomassie blue B) ! -mercaptoethanol C) glutathione D) phenylisothiocyanate E) Fmoc F) guanidine hydrochloride G) Dicyclohexylcarbodiimide (DCC) H) HF I) Dansyl chloride 12. Forms a derivative with the N-terminal amino acid in Edman Process of protein sequencing. 13.
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10.09 - Examination I - Name: _ 1 General Biochemistry Exam...

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