Fall05midterm

Fall05midterm - NOTE: The figures for a couple of problems...

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NOTE: The figures for a couple of problems are currently missing due to a computer problem. I will post the missing figures as soon as possible. 1. Fill in the following table with the 3 letter code for 2 different amino acids that have the following characteristics: (2 points each) Characteristic Amino Acid #1 Amino Acid #2 Negatively charged R group Aromatic Contain sulfur Contain OH group 2. Rank the following amino acids in order of the one that is LEAST soluble in an aqueous environment to the one that is MOST soluble in an aqueous environment. (3 points, all or nothing) His, Phe, Ser, Ile, Asp, Trp 3a) Give the full amino acid name and ONE letter code for the side chains in the following peptide: Numbering begins at the N terminus of the peptide. (2 points each) Name of amino acid One letter code #1 #2 #3 #4 #5 b) What is the overall NET charge on this peptide at pH 7? Show how you got your answer. (3 points) c) Which of the amino acids in this peptide could form H-bonds? (2 points) d) Where would you be most likely to find this peptide in a protein (i.e. core, surface) and WHY? (4 points) 1
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___________________________ Last Name, First 4. Which of the following amino acid substitutions would be considered conservative (i.e. the substitution maintains the characteristic of the amino acid)? Check YES if the substitution is conservative and NO if it is not conservative. (2 points each) YES NO Lys to Glu Arg to Asp Val to Leu Gln to Asn Ala to Thr 5. The following sentences may be TRUE or FALSE. If they are TRUE, then just write TRUE. IF they are FALSE, then CORRECT the sentence by replacing or crossing out a word or two. (3 points each) a. Hydrogen bonding occurs between NH and C=O groups in an α helix b. The R groups face inwards in an α helix c. The main chain of a protein is hydrophobic d. Several Lys residues in a row would help stabilize an α helix e. GLU at the N-terminal end of an α helix would help stabilize it. f. In a helical wheel, amino acids are plotted every 5.4 Angstroms around a circle g. In a β sheet, all of the R groups protrude on the same side of the sheet h. A β turn often connects 2 adjacent antiparallel β strands i. Weak interactions that help to stabilize protein structures include disulfide bonds, hydrogen bonds and hydrophobic interactions. j.
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Fall05midterm - NOTE: The figures for a couple of problems...

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