1. BC 367 Review Questions for Exam 1

2. 250 mL of 1.0 M HCl is added to 1.0 L of a 1.0 M acetic acid/sodium acetate buffer at pH 4.76 (pKa = 4.76). What is pH of the final solution? A. 5.24 B. 4.28 C. 4.55 D. 3.86 E. 4.76 (this is a buffer!)

3. What effect would hypoventilating (slow and shallow breathing) have on the blood? a)No change in blood pH. b)A decrease in [CO 2 ], causing an increase in [H + ] and decrease in pH. c)An increase in [CO 2 ], causing an increase in [H + ] and decrease in pH. d)A decrease in [CO 2 ], causing an increase in [H + ] and increase in pH. e)An increase in [CO 2 ], causing a decrease in [H + ] and increase in pH.

4. This titration curve is for what amino acid? http://cti.itc.virginia.edu/~cmg/Demo/markPka/markPkaApplet.html a) Arg b) His c) Leu d) Cys e) Glu

5. You want to separate a mixture of three hypothetical proteins, all of which repeat certain amino acid sequences. The sequences and their masses are below. What should you use to best separate these proteins? Protein Repeating amino acid sequence MrMr Protein 1Val-Lys-Arg22 900 Protein 2Gln-Phe-Gly59 000 Protein 3Asp-Leu-Glu23 100 A. Gel filtration column B. CM-sephadex column run at pH 7 C. Gel electrophoresis D. Affinity chromatography E. Paper chromatography

6. Which of these peptides would be least soluble in a solution at a pH of 5.5? a) (Arg-Gly) 2 b) (Met-Asp-Val) 3 c) (Phe-Lys) 5 d) (Asn-Phe-Gln) 3 e) (Ala-Pro-Ile) 3

7. A peptide was exposed to two separate enzyme digests to yield the fragments shown below. At physiological pH, what is the approximate net charge of the last five residues prior to digestion? Chymotrypsin Trypsin Arg-Trp Trp-Lys Asp Met-Phe-Asp Lys-Arg-Met-Phe Leu-Phe-Arg Lys-Leu-Phe Lys Arg A) -1 B) 0 C) +1 D) +2 E) Not enough information

8. Which one of the following peptides is most likely to adopt an alpha helix? A) Arg-Thr-Ile-Val-Tyr-Phe-Trp-Ile B) Arg-Ala-Trp-Glu-Gly-Arg-Arg-Asp C) Ala-Glu-Leu-Ala-Lys-Ala-Met-Asp D) Val-Thr-Gly-Pro-Thr-Asn-Pro-Arg E) None of these peptide will be alpha helical because they all contain left- handed amino acids.

9. Protein A contains 1000 amino acids and has a unit evolutionary period of 6 million years. Protein A has an ortholog in another species that diverged 12 million years ago. How many amino acids differ between the sequences of the two orthologs of protein A? A.200 B.100 C.20 D.10 E.2