Homework Assignment 6

Homework Assignment 6 - Dr Leisha Mullins BIOCHEMISTRY...

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Unformatted text preview: Dr. Leisha Mullins BIOCHEMISTRY 411/602 Print Name: ________________ Spring 08 Homework Assignment 6 Sign Name: ______________ 10 points BIOCHEMISTRY 411/602 Homework Assignment 6 Due: Tuesday March 4,2008 1 (2 pts). Write a balanced net reaction for the conversion of each of the following to CO2 via glycolysis, the citric acid cycle, and oxidative phosphorylation (as required). What is the net yield of ATP? (1 NADH = 2,5ATP, 1 FADH2 = 1.5 ATP). A. pyruvate pyruvate + CoA + NAD Acetyl-Co A + CO2 + NADH Acetyl-Co A + OAA + H2O + 2 NAD + GDP + Pi Succinate + 2 CO2 + 2 NADH + GTP Succinate + FAD + H2O + NAD OAA + FADH2 + NADH NET: pyruvate + 4 NAD + FAD + 2 H2O+ GDP + Pi 3 CO2 + 4 NADH + FADH2 + GTP 4 NADH x 2.5 ATP/NADH + 1 FADH2 x 1.5 ATP/FADH2 + 1 GTP(ATP) = 12.5 ATPs B. lactate 15 ATP's Lactate + NAD pyruvate + NADH pyruvate + CoA + NAD Acetyl-Co A + CO2 + NADH Acetyl-Co A + OAA + H2O + 2 NAD + GDP + Pi Succinate + 2 CO2 + 2 NADH + GTP Succinate + FAD + H2O + NAD OAA + FADH2 + NADH NET: Lactate + 4 NAD + FAD + 2 H2O+ GDP + Pi 3 CO2 + 4 NADH + FADH2 + GTP 5 NADH x 2.5 ATP/NADH + 1 FADH2 x 1.5 ATP/FADH2 + 1 GTP(ATP) = 15 ATPs C. glycerol glycerol + ATP + NAD GAP + ADP + NADH GAP + NAD + Pi + 2 ADP Pyruvate + NADH + 2 ATP pyruvate + CoA + NAD Acetyl-Co A + CO2 + NADH Acetyl-Co A + OAA + H2O + 2 NAD + GDP + Pi Succinate + 2 CO2 + 2 NADH + GTP Succinate + FAD + H2O + NAD OAA + FADH2 + NADH NET: glycerol + 6 NAD + FAD + 2 H2O+ 1 ATP +GDP + Pi 3 CO2 + 6 NADH + FADH2 + ADP +GTP 6 NADH x 2.5 ATP/NADH + 1 FADH2 x 1.5 ATP/FADH2 + 1 GTP(ATP) +1 ATP= 18.5 ATPs D. Acetyl-CoA Acetyl-Co A + OAA + H2O + 2 NAD + GDP + Pi Succinate + 2 CO2 + 2 NADH + GTP Succinate + FAD + H2O + NAD OAA + FADH2 + NADH NET: Acetyl-Co A + 3 NAD + FAD + H2O+GDP + Pi 2 CO2 + 3 NADH + FADH2 + GTP 3 NADH x 2.5 ATP/NADH + 1 FADH2 x 1.5 ATP/FADH2 + 1 GTP(ATP) = 10 ATPs 2 (2 pts). Draw an O2 consumption curve for a suspension of isolated mitochondria when the following compounds are added in the indicated order. Indicate on the curve the effect of each compound as it is added. With the addition of each compound, all of the previously added compounds remain present. The experiment starts with a high concentration of O2. The oxygen concentration can only decrease or be unaffected. Indicate on the graph the effect of each compound as it is added. a. NADH added b. ADP added c. Rotenone added d. Succinate added e. ADP runs out f. DNP added Dr. Leisha Mullins BIOCHEMISTRY 411/602 Print Name: ________________ Spring 08 Homework Assignment 6 Sign Name: ______________ 3 (3pt). What would be the yield of ATP from the complete oxidation of glucose (by glycolysis, citric acid cycle, and oxidative phosphorylation) if the Q cycle had only one phase (if both electrons from the original QH2 passed to the ISP and cyt C1)? In oxidative phosphorylation, assume the F1F0 ATP Synthase can generate one ATP for every three H+ translocated. Please be sure to indicate where every NADH and FADH2 comes from. Count protons translocated via the protein complexes in the ETC. In electron transport, Complex III has been compromised so for every NADH that enters only 8 protons (i.e 2.7 possible ATP) are translocated and for every FADH2 only 4 protons translocated ( i.e 1.3 ATP) . For glycolysis 2 ATP, 2 NADH, 2 pyruvate Pyryvate dehydrogenase complex ( 2 pyruvates entering) 2 NADH , 2 acetyl-CoA TCA ( 2 acetyl-CoA) 6 NADH, 2 FADH2, 2 ATP Total 10 NADH, 2 FADH2, 4 ATP ( assuming malate aspartate shuttle) 1st way: 2nd way: 3rd way: 10 NADH 27 ATP 10 NADH 80 protons 26 ATP 10 NADH 80 protons 2 FADH2 2 ATP 2 FADH2 8 protons 2 ATP 2 FADH2 8 protons 4 ATP 4 ATP 88 protons 33 ATP 32 ATP 88 protons 29 ATP 4 ATP 33 ATP IF you used 1 ATP / 4 H+ translocated (synthesis and transport) NADH 8 protons (i.e 2 possible ATP) are translocated and for every FADH2 only 4 protons translocated ( i.e 1 ATP) 1st way: 2nd way: 3rd way: 10 NADH 20 ATP 10 NADH 80 protons 20 ATP 10 NADH 80 protons 2 FADH2 2 ATP 2 FADH2 8 protons 2 ATP 2 FADH2 8 protons 4 ATP 4 ATP 88 protons 26 ATP 26 ATP 88 protons 22 ATP 4 ATP 26 ATP 4 (1pts). A. Calculate the proton motive force across the inner mitochondrial membrane at 25C when the electrical is 0.018V (inside negative) and the pH outside is 6.3 and the pH INSIDE is 7.2 B. What percentage of the free energy is from the chemical gradient and what percentage is from the charge gradient? G = 2.3 RT [ pH (in) pH (out) ] + ZF G = 2.3 (.008315)(298k) [ 7.5 6.7 ] + (+1) (96 ) (0.18 V) G = 4.56 + 17.28 = 21.84 kJ /mol Chemical gradient 4.56/ 21.84 = 21% Charge gradient 17.28/ 21.84 = 79 % 5 (2 pt). A. What would be the effect of a relatively low and a relatively high concentration of uncoupling agent on the rate of electron transfer and the P/O ratio? Neither would affect the electron transfer chain but the P/O ratio would be slightly lower in the presence of a low concentration of an uncoupler it would be extremely low or 0 (i.e. electron transport and oxidative phosphorylation are uncoupled) in the presence of a high concentration B. Explain in molecular terms why ingestion of uncouplers causes an increase in body temperature and profuse, disgusting sweating. What happens to the P/O ratio in the presence of uncouplers? Increase in catabolism (glycogen and lipid) in an attempt to generate ATP, so "burning" more fuel, also uncouplers are dissipating gradient and some energy can be lost as heat, P/O ratio will decrease C. Certain uncouplers were once prescribed as weight reducing drugs. However, they are no longer prescribed due to some fatalities following their use. Why might the ingestion of uncouplers lead to death? If completely uncouple electron transport and oxidative phosphorylation then only ATP made is as a result of substrate level phosphorylation. ...
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