Biochemistry 460 Exam #3 Form A: Biochemistry Questions with Answers and Calculations, Exams of Biology

Download Biochemistry 460 Exam #3 Form A: Biochemistry Questions with Answers and Calculations and more Exams Biology in PDF only on Docsity! WRITE YOUR NAME AND I.D. NUMBER LEGIBLY ON EVERY PAGE – PAGES WILL BE SEPARATED FOR GRADING! CHECK TO BE SURE YOU HAVE 6 PAGES, NAME (print): INCLUDING COVER PAGE. 5-digit course ID # I swear/affirm that I have neither given nor received any assistance with this exam. Signature: Date: BIOCHEMISTRY 460 THIRD HOUR EXAMINATION FORM A April 10, 2006 A NON-PROGRAMMABLE CALCULATOR MAY BE USED ON THIS EXAM. No programmable calculators are permitted, and no sharing of calculators. We have a couple of spare calculators to lend in an emergency. SHOW YOUR WORK FOR ALL CALCULATIONS, AND BE SURE TO STATE UNITS OF ANY NUMERICAL ANSWERS. If the reasoning, calculations, or answer are shown anywhere other than in the space provided, make a note in the space provided and put answer on BACK OF SAME PAGE so the grader for that page will have it. USEFUL CONSTANTS: R (gas constant) = 8.315 J•mol–1•Kelvin–1 = 8.315 x 10–3 kJ•mol–1•Kelvin–1 F (Faraday Constant) = 96.48 kJ•V–1•mol–1 If temperature = 25 °C, absolute temperature T = 298 K (Assume this temperature unless problem states otherwise.) Potentially useful equations: Energy Charge (EC): [ATP]+ 0.5[ADP] [ATP]+ [ADP]+ [AMP] Change in Free Energy: ΔG'= ΔGº'+RT ln [product]actual [substrate]actual At equilibrium (when ΔG’ = 0): ΔGº'= −RT ln [product]equilibrium [substrate]equilibrium Change in Reduction Potential: ΔEº'= (Eº'e- acceptor ) − (Eº'e- donor) Relating ΔGº' to ΔEº': ΔGº'= −nFΔEº' Biochemistry 460, Exam #3 Form A NAME April 10, 2006 5-digit course ID# page 2 1. (5 pts) How are G Proteins inactivated (reset)? 2. (6 pts) Mutations in the protein Ras have been implicated in a number of cancers. The most common of these mutations is a glycine to valine substitution at codon 12. Why does a mutation at this position cause cancer? 3. (5 pts) Cyclic AMP (cAMP) was discussed in detail in class and in the text. What role does cAMP play in the glucagon stimulated signaling pathway and how is it made? 4. (6 pts) Define or explain the “Energy Charge” of a cell, and explain in general terms why catabolism is favored under conditions of low Energy Charge in the cell. (You do NOT need to discuss specific reactions that are regulated.) p. 2 (22 points) p. 3 (25 points) p. 4 (23 points) p. 5 (14 points) p. 6 (16 points) TOTAL: (100 points) /22 Biochemistry 460, Exam #3 Form A NAME April 10, 2006 5-digit course ID# page 5 12. (14 pts) Compare mitochondrial electron transport system (ETS) and oxidative phosphorylation with the photosynthetic electron transport system and photophosphorylation, by filling in the table below from the following choices: cytosol NADP+ plasma membrane NADPH chloroplast stroma NAD+ chloroplast thylakoid space (thylakoid lumen) NADH nucleus β-carotene mitochondrial matrix chlorophyll mitochondrial intermembrane space (between inner and outer membranes) pheophytin F0F1 ATP synthase plastoquinone (PQ) succinate dehydrogenase ubiquinone (Coenzyme Q) cytochrome b6f complex O2 photosystem I H2O alternative oxidase ATP complex IV ADP ferredoxin AMP thioredoxin cAMP Not in this system Mitochondrial ETS & Ox.Phos. Photosynthetic ETS & Photophos. Original electron donor for ETS Terminal electron acceptor for ETS Mobile protein electron carrier between protein complexes Mobile lipid electron carrier between protein complexes Where is ATP made? Protein that pumps protons Converts light energy into charge separation /14 Biochemistry 460, Exam #3 Form A NAME April 10, 2006 5-digit course ID# page 6 13. (10 points) A group of biochemists studied the Calvin Cycle enzyme, fructose-1,6-bisphosphatase (FBPase), from a plant. They analyzed activity of the enzyme under different conditions. To their surprise, they found that this enzyme was regulated in a manner similar to rubisco. They plotted their data and obtained the graph below. C. (2 pts) When would you expect physiological conditions around the enzyme in the plant to be similar to those of the two points indicated on the graph? Circle correct answer: Point A: Day / Night / Conditions around the enzyme are always like this in the cell. Point B: Day / Night / Conditions around the enzyme are always like this in the cell. 14. (6 pts, 3 pts each) Insert the appropriate word(s) to make the statements correct. A. C4 photosynthesis involves separation in __________________ for CO2 uptake and CO2 fixation. B. CAM photosynthesis involves separation in ________________ for CO2 uptake and CO2 fixation. A B A. (2pts) Where is this Calvin Cycle enzyme (FBPase) localized in the cell? B. (6 pts) What does this graph tell you about the regulation of this enzyme? In other words, what processes in the plant lead to the stimulation of the activity of this enzyme and why? /16