Question

1. Compare and contrast oxidative phosphorylation and the citric acid cycle. (20 pts total) 1 i) Explain how they are similar in location, and how they are different in location. (10 pts) 1 li) Other than being a component of cellular respiration explain how they are similar in function, and how they are different in function. (10 pts) 2. When you lose weight, where does the carbon go that was in your fat? (20 pts) 3. Aerobic cellular respiration requires enzymes for energy production (20 pts tot 31) What is the balanced chemical I equation for aerobic cellular respiration using glucose as a substrate? (10 pts) 3 il) If this balanced chemical equation for aerobic cellular respiration was in equilibrium, what would happen if you added more enzymes? Justity your answer. (10 pts) 4. Propose an experiment to distinguish a noncompetitive inhibitor from a competitive inhibitor, and you would look for as an outcome in your experiment to conclude that you have a competitive inhib explain what itor. (20 p ts) Extra Credit - Cyanide is a mitochondrial poison that inhibits the electron transport chain. What would you predict would happen to oxygen levels in the blood after cyanide poisoning? Justify your answer. (8 points extra O43100 09918T

Answer 1

1i. Similarity and differences in the location of citric acid cycle and oxidative phosphorylation- The similarity is that both processes occur in the mitochondria. However, the citric acid cycle takes place in the matrix of the mitochondria where the reduced electron carriers are i.e. NADH and FADH2 are generated during the cycle, while the process of oxidative phosphorylation takes place in the inner mitochindrial membrane where the respiratory chain or successive electron carriers are present which accept electron and create a proton gradient across the inner mitochondrial membrane. In oxidative phosphorylation, the final electron acceptor is the molecular oxygen and the energy generated as a proton graient across the membrane drives the formation of high energy bonds of ATP.

ii. Similarity and differences in the function of citric acid cycle and oxidative phosphorylation- Similarity is that both procsses are part of aerobic respiration that leads to generation of the energy currency of the cell ATP. Apart from this the other similarity is that the cycle and the respiratory chain both harness the reduction and oxidation cycles of NAD, FAD and NADH and FADH2 respectively. The Difference is that citric acid cycle is a very important part of the intermediary metabolism. It gets fed from the catabolism of amino acids and fatty acids while some of its intermediates are also used for the biosynthesis of amino acids, fatty acids, purines and pyrimidines. The oxidatitive phosphorylation on the other hand is mostly involved in generation of ATP by chanelling the electrons and protons from the NADH and FADH2 into electron carrier complexes and finally to the oxygen. The only feed into the process of oxidative phosphorylation is the reduced NADH and FADH2, the levels of which in turn may be affected by the intermediary metabolism.

2. The carbon in the fat is mostly in the form of long chain fatty acids. When one looses weight it means the fatty acids are being oxidised. This is done by the process of beta oxidaton of fatty acid. The carbon is fed into the citric acid cycle by the process of beta oxidation of fatty acids. Therefore since it enters into the citric acid cycle, some of the carbon is released as co2, while some as intermediates of the cycle may get used up in the biosymthesis of amino acids, purines and pyrimidines.

3i.

H12 %+ 60 6CO2 +6H20 + 2900 kJ/mol

This is a balanced chemical equation which shows that 1 moles of glucose is oxidised with 6 moles of oxygen to form six moles each of carbon dioxide an water. approx 2900 KJ of energy is produced in the process which is stored in form of approximately 38 molecules of ATP.

ii. If this balanced chemical equation was in equillibrium and one adds more enzyme, the rate of the reaction or the state of equilbrium would not be altered as the state of equilibrium can only be altered by the changein the concentration of reactants i.e. the glucose and oxygen or the products i.e. the carbon dioxide, water and ATP.

4. A suitable experiment to distinguish between a competetive inhibitor and non competetive inhibitor is by measuring the rate of reaction at different substrate concentration both in the presence and absence of the test compound, followed by plotting the double reciprocal graph or the lineweaver burk plot. If the test compound is a competetive inhibitor, the y-intercept that is 1/vmax is unaltered in the presence and absence of the compound while the slope of the graph i.e. the km/vmax will change as also the x-intercept or km. In case if the test compound is non competetive inhibitor,both the slope and Y-intercept will change as the vmax will be reduced but the x-intercept i.e. the km will remain unaltered in the presence and absence of the test compound. The image from wikipedia will make the concept more clear

Lineweaver-Burk plots for enzyme inhibition -inhibitor - no inhibitor - inhibitor - no inhibitor - inhibitor -no inhibitoi I/V 1/V l/V Slope: change Y-intercept: same Slope: same Y-intercept: change Slope: change Y-intercept: change 1/[S] 1/[S] 1/[S] Competitive inhibition KM increased Vmax unaffected Uncompetitive inhibition KM reduced Vmax reduced Noncompetitive (Mixed) inhibition KM unaffected Vmax reduced

In cyanide poisoning since the electron chain is disrupted, the oxygen within the cell will remain unused,so that the oxygen pressure in the cells or tissues will not drop to allow the heme bound oxygen in blood RBC to be released or become deoxygenated. Since the oxygen will not be released into the cells its level should theoretically increase in the blood.