Question

4. Noncompetitive inhibitors: a) bind to the active site b) bind to the enzyme-substrate complex c) bind outside the active site and decrease substrate binding d) bind outside the active site and decrease rate of catalysis. 5. Which statement best describes the effect of pH upon enzyme catalyzed reactions? a) rate increases with increasing pH b) rate decreases with increasing pH c) rate increases with increasing pH until the denaturation pH is reached d) every enzyme has an optimum pH at which catalysis is fastest. Chapter 9. Hemoglobin and Myoglobin 1. Which of these is not found in myoglobin? A) alpha helix b) beta sheet c) heme group d) globular folding pattern 2. Which statement about hemoglobin is not true? A) it is globular b) it contains helix- loop-helix c) it has three subunits d) it has heme groups The molecule which binds in the central cavity of hemoglobin when it is deoxygenated 3. is: a) CO2 b) heme c) BPG d) all of these 4. The transition of hemoglobin from its T-form to its R-form results in: a) Loss of BPG b) release of CO2 c) cooperative oxygen binding behavior d) conversion of alpha helix to beta sheet The indirect effect of CO2 is a result of formation of while the direct effect of 5. CO2 is the result of the formation of A) heme, BPG B) alpha helix, beta sheet C) carbonic acid, N-terminal carbamate d) carbonic acid, BPG The iron in heme in hemoglobin and myoglobin binds to oxygen. It also binds to : a) BPG 6. b) CO2 c) proximal His d) distal His 7. The oxygen molecule which binds to the heme iron in hemoglobin and myoglobin also binds to: : a) BPG b) CO2 c) proximal His d) distal His 8. Which statement about sickle cell hemoglobin is not true? A) it is fibrous in its deoxygenated form b) it has Val instead of Glu in position 6 of the beta chain c) It has lost its heme groups d) it offers resistance against malaria 9. A person with sickle-cell disease would have about what % sickled cells? A) 100 % b) 50% c) 5 % d) 1 % 10. Beta thalassemia is named such because: a) the patient's hemoglobin contains mostly beta sheet. B) the patient lacks the gene for the beta subunit of hemoglobin, resulting in tetramers of the alpha subunit c) the patient lacks the gene for the alpha subunit of hemoglobin, resulting in tetramers of the beta subunit d) in beta thalassemia, the herme groups are bonded to beta barrel motifs