10. When oxygen binds to a heme-containing protein, the two open coordination bonds of Fe²⁺ are occupied by:
(A) one O atom and one amino acid atom.
(B) one O₂ molecule and one amino acid atom.
(C)one O₂ molecule and one heme atom.
(D) two O atoms.
(E) two O₂ molecules.

6. Which of the following best represents the backbone arrangement of two peptide bonds? (A) Cα-N-Cα—C—Cα-N-Cα-C (B) Cα-N-C—C—N-Cα (C)C-N-Cα—Cα—C-N (D) Cα-C-N-Cα-C-N (E) Cα-Cα-C-N-Cα—Cα—C

7. Thr and/or Leu residues tend to disrupt an α helix when they occur next to each other in a protein because: (A) an amino acids like Thr is highly hydrophobic. (B) covalent interactions may occur between the Thr side chains. (C)electrostatic repulsion occurs between the Thr side chains. (D) steric hindrance occurs between the bulky Thr side chains. (E) the R group of Thr can form a hydrogen bond.

8. The tripeptide glycylarginylglutamate contains four ionizable groups with pKas of 2.1, 4.1 9.8, and 12.5. Calculate the pI for this molecule. (A) 3.1 (B) 6.4 (C)7.0 (D) 7.3 (E) 8.3

9. The quantitation of proteins due to their absorbance at ~280 nm (UV region) is due to the large absorptivity of the ______ amino acids. (A) anionic (B) dansylated (C)cleaved (D) polar (E) aromatic

11. 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.

12. Which one of the following statements is true of enzyme catalysts? (A) Their catalytic activity is independent of pH. (B) They are generally equally active on D and L isomers of a given substrate. (C)They can increase the equilibrium constant for a given reaction by a thousand fold or more. (D) They can increase the reaction rate for a given reaction by a thousand fold or more. (E) To be effective, they must be present at the same concentration as their substrate.

13. Which of the following statements about a plot of Vo vs. [S] for an enzyme that follows Michaelis-Menten kinetics is false? (A) As [S] increases, the initial velocity of reaction Vo also increases. (B) At very high [S], the velocity curve becomes a horizontal line that intersects the y-axis at Km. (C)Km is the [S] at which V0 = 1/2 Vmax. (D) The shape of the curve is a hyperbola. (E) The y-axis is a rate term with units of µm/min.

14. Which of the following monosaccharides is not an aldose? (A) erythrose (B) fructose (C)glucose (D) glyceraldehyde (E) ribose

15. From the abbreviated name of the compound Gal(β1 → 4)Glc, we know that: (A) C-4 of glucose is joined to C-1 of galactose by a glycosidic bond. (B) the compound is a D-enantiomer. (C)the galactose residue is at the reducing end. (D) the glucose is in its pyranose form. (E) the glucose residue is the β anomer.

16. In the laboratory, recombinant plasmids are commonly introduced into bacterial cells by: (A) electrophoresis – a gentle low-voltage gradient draws the DNA into the cell. (B) infection with a bacteriophage that carries the plasmid. (C)microinjection. (D) mixing plasmids with an extract of broken cells. (E) transformation - heat shock of the cells incubated with plasmid DNA in the presence of CaCl2.