Question

1. Explain how aerobic pathways permit generation of more ATP than anaerobic pathways.

2. Explain the 2 stages of oxidative phosphorylation

3. Explain how the electron transport chain can establish an electrochemical gradient across the inner membrane (what is it about this process and the proteins involved in the process that allows the formation of this electrochemical gradient?)

4. Discuss the relative affinity for electrons of the electron acceptors of the different respiratory complexes (which complexes would you expect to have higher affinity for electrons, those that accept electrons early in the chain, or those that accept electrons near the end of the chain?)

Answer 1

1. In anaerobic pathway, 2 ATP molecules are produced per hlucose pathway because only glycolysis is being carried out. The citric acid cycle and electron transport chain are not functional in anaerobic pathways which leads to lesser energy production.

2. The two stages are Electron transport chain and Chemisomosis. Reduced FADH2 and NADH transfer their electron to molecules in electron transport chain which are low in energy. Some of the energy is released which is used to transfer H+ ions across the innner membrane of mitochondria from the mitochondrial matrix to the inner membrane space . It results into development of electrochemical gradient. This process is called chemisomosis. Finally electron is accepted to form the water.

3.Complex I, III and IV are proton pumps which move protons form matric to inter membrane space causing a proton motive force to develop. The enegy for this movememt is harnessed by relesed energey ehen electron is being transferred to a lower enery molecule in the chain. Now the protons can not move diectly through the inner membrane which has a very hydrphobic core. Hence specific channels are found in the membranelike hydrpophilic tunnels which allow the protons to move across. This channel is formed a membrane spanning protein called ATP synthetase which allows protons to pass through it. Now this syntehtase acts as turbine which moves by protons when they pass though it and this movement of the synthetase allows catalysis of phosphate to ADP which results into the formation of ATP.

4. The potential of accepting any electron by electron acceptors depends on the standard reduction poteintial. The acceptors with highest redox potential (most positive) will have the highest capacity for electron. Hence from complex I to O2 the value of standard redox poteitial increses and hence electron intake capacity increses.