Quiz 2, BICH 410 (MWF3-3:50), Friday, Oct. 9, 1998
Clearly circle the letter corresponding to your answer for each problem. There are six problems, four of which count 3 points, and two for 4 points. No partial credit given for multiple-choice questions.
gas constant R 8.315 J/mole-K
1. (4 pts.) Which of the following statements is not true about the T state of hemoglobin?
Answer: C; see Problem 5 in Chap. 7
- A) The affinity for oxygen is lower for the T state than for the R state.
- B) The binding of BPG stabilizes the T state relative to the R state.
- C) The P50 for the T state is lower than that for the R state.
- D) The T state corresponds to deoxygenated hemoglobin.
- E) All of the above statements are true.
2. The Hill coefficient, nH is:
Answer: D; see Problems 5 and 7 from Chap. 7; E is not correct because the Hill coefficient would be less than one for negative cooperativity
- A) equal to one for hemoglobin.
- B) equal to the number of binding sites for oxygen in hemoglobin.
- C) the pO2 where the maximum slope of the Hill plot intersects the x-axis.
- D) the maximum slope of the Hill plot.
- E) always greater than one for any protein that exhibits cooperativity.
3. Starch and glycogen are both polymers of:
- A) alpha-D-glucose
- B) beta-D-glucose
- C) sucrose
- D) alpha-D-galactose
- E) cellulose
4. Which of the following statements is true about the structure of an IgG molecule?
- A) contains four subunits
- B) binds two molecules of antigen
- C) The structure of the antigen-combining site is characterized by a beta-beta sandwich known as the immunoglobulin fold.
- D) Careful proteolysis generates two Fab fragments.
- E) All of the above are true.
5. (4 pts.) Given the following hypothetical disaccharide molecule:
beta-D-galactopyranosyl-(1 -> 2)-alpha-D-fructofuranoside
Which of the following statements is not true regarding this disaccharide?
Answer: D; these two monosaccharides are linked via an O-glycosidic bond between the two anomeric carbons; hence there is no reducing end
- A) The fructose residue is cyclized into a five-membered ring.
- B) The two monosaccharides are linked via an O-glycosidic linkage.
- C) This disaccharide will not reduce Fehling's reagent.
- D) The galactose residue is the non-reducing end, and the fructose residue is the reducing end.
- E) The galactose residue is cyclized into a six-membered ring.
6. Sickle cell hemoglobin (HbS) is characterized by the following:
- A) The T to R transition is blocked.
- B) The proximal histidine residue has been mutated to a valine, causing the heme group to be only loosely attached to hemoglobin.
- C) The subunits are more easily dissociated than for normal hemoglobin.
- D) A single valine substitution on the beta subunit causes the protein to aggregate into long strands.
- E) The inherent oxygen affinity is much lower than for normal hemoglobin.