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 K_m.
(C)Km is the [S] at which V₀ = 1/2 V_max.
(D) The shape of the curve is a hyperbola.
(E) The y-axis is a rate term with units of µm/min.

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

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.

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.

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.

17. In an anaerobic muscle preparation, lactate formed from glucose labeled in C-3 and C-4 would be labeled in: (A) all three carbon atoms. (B) only the carbon atom carrying the OH. (C)only the carboxyl carbon atom. (D) only the methyl carbon atom. (E) the methyl and carboxyl carbon atoms.

18. Glucose labeled with 14C in C-1 and C-6 gives rise in glycolysis to pyruvate labeled in: (A) A and C. (B) all three carbons. (C)its carbonyl carbon. (D) its carboxyl carbon. (E) its methyl carbon.

19. Inorganic fluoride inhibits enolase. In an anaerobic system that is metabolizing glucose as a substrate, which of the following compounds would you expect to increase in concentration following the addition of fluoride? (A) 2-phosphoglycerate (B) Glucose (C)Glyoxylate (D) Phosphoenolpyruvate (E) Pyruvate