Exam 2 (2007) - University of Houston BCHS 3304 Exam II...

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1 University of Houston BCHS 3304 Exam II Instructor Dr. Briggs Mar. 06, 2007 Printed Name___ANSWER KEY _______ LAST, FIRST Multiple choice, 2 pts each (100 pts) – Circle letter (i.e. a., b., c., d., or e.) of the most correct answer, then mark it on the Scantron sheet with a #2 pencil. Mark BOTH the exam AND the Scantron sheet. A Ramachandran plot can be found at the end of the exam. 1). Binding of oxygen to the heme in either myoglobin or hemoglobin requires: a). A heme-heme dimer complex. b). A iron liganded to a tyrosine. c). His F8 linked to the iron d). His E7 linked to the iron e). The iron in the +3 oxidation state 2). What is the N M nomenclature for an alpha helix? a). 2.2 7 b). 4.4 16 c). 3.6 13 d). 3 13 e). None of the above. 3). What percentage of CO 2 is transported by hemoglobin via formation of carbamates? a). 5% b). 25% c). 50% d). 75% e). 100% This question is not worded clearly enough so answers “a” and “c” will be marked as correct. 4). What is the effect on hemoglobin at high altitudes when the 2,3-BPG concentration in the blood rises from 5 mM to 8 mM? a). More CO 2 is released. b). More oxygen is released. c). The concentration of glucose increases. d). More hemoglobin is degraded. e). The myoglobin concentrations are low.
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2 5). The slope of the Hill plot for oxygen binding to hemoglobin changes and becomes greater than 1 as compared to the slope of the Hill plot for oxygen binding to myoglobin which is always 1: a). This indicates that myoglobin can release more O 2 than hemoglobin. b). This indicates that hemoglobin exhibits negative cooperativity. c). This indicates that hemoglobin exhibits positive cooperativity. . d). This indicates the binding of one molecule of O 2 to hemoglobin enhances the release of another. e). This indicates that carbon monoxide irreversibly binds to both proteins. 6). What is the ionic strength, I, of a 9M solution of Ca 3 (PO 4 ) 2 ? a). 135 M b). 45 M c). 270 M d). 450 M e). 180 M I=0.5*Sum(c i *Z i 2 )=0.5*{[3*9M]*(2) 2 + [2*9M]*(-3) 2 }=0.5{108+162} = 135M 135M [Ca 2+ ] [PO 4 3- ] (These were inadvertantly given as 270, 90, 540, 900, and 360 M on the exam but I gave the correction, as above, on the board and announced it) 7). Calculate the length in angstroms of a 1024-residue segment of the α -keratin coiled-coil. a). 35 Å b). 1024 Å c). 179 Å d). 1492 Å e). 1536 Å 8). The φ dihedral angle of a peptide bond is described by rotation about the bond a). that is between the N and C atoms. b). that is between the C α and C atoms. c). that is between the C α and C β atoms. d). that is between the C α and N atoms. e). none of the above. 9). The ψ dihedral angle of a peptide bond is described by rotation about the bond a). that is between the N and C atoms. b).
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This note was uploaded on 12/02/2011 for the course BCHS 3304 taught by Professor Johnson during the Spring '08 term at University of Houston.

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Exam 2 (2007) - University of Houston BCHS 3304 Exam II...

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