Term
Describe what happens to each of the following during a redox reaction
Oxidizing agent
Reducing agent |
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Definition
1. Reducing agent - Reducing agents donate electrons to the oxidizing agent, thus becoming oxidized themselves
2. Oxidizing agents - accept electrons from the reducing agent, thus becoming reduced themselves |
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Term
| What is the difference between electron only and reducing-equivalent redox reactions and which type occurs more often biologically? |
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Definition
Electron only involves the exclusive transfer of electrons whereas reducing-equivalent reactions involve the movement of protons and electrons.
Reducing equivalent is more common (ex. Pyruvate to lactate with paired oxidation of NADH) |
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Term
| How do you calculate the EMF for a redox reaction? |
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Definition
| Eacceptor-Edonor. The acceptor will have a higher redox potential then the donor. |
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Term
| How are EMF and change in free energy related? |
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Definition
G = -nFE
(positive E's lead to spontaneous reactions) |
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Term
| Provide the steps in the electron transport chain |
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Definition
1. NADH Dehydrogenase removes electrons from NADH and passes them to Coenzyme Q
2. Complex 1 pumps 4 Hydrogens across the membrane into the intermembrane space
3. Complex 2 takes the electrons from FADH2 and passes them to Coenzyme Q
4. Coenzyme Q passes the electrons on to the heme carrier in complex 3 which passes them to Cytochrome C and pumps 4 protons across the membrane in the process
5. Cytochrome C passes the electrons to Complex 4
6. Complex 4 passes the electrons to O2 and pump 2 more hydrogens across the membrane |
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Term
| How are electrons passed from compound to compound in the electron transport system? |
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Definition
| Each subsequent step has a higher redox potential so it has a higher electron affinity to accept electrons. |
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Term
| How does cyanide poisoning work? |
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Definition
| CN binds to the Fe+++ in complex IV and prevents O2 reduction by the electrons. |
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Term
| What are 2 possible treatments of cyanide poisoning? |
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Definition
| Treatment with Nitrites or thiosulfate |
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Term
| What is the proton motive force and what does it govern? |
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Definition
1. An electrochemical gradient of protons across the inner membrane of mitochondria
2. Energy released by allowing protons to travel down their gradient is harnessed to fuel ATP synthesis |
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Term
| Explain how the ATP synthase complex works. |
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Definition
| Protons traveling through F0 cause the c, epsilon, and gamma subunits to rotate. This rotation causes conformation changes in alpha and beta subunits (anchored to delta and b2 subunits). These conformational changes drive ATP synthesis |
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Term
| What measurement represents how tightly coupled electron transport and oxidative phosphorylation are and explain the underlying mechanism of this coupling. |
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Definition
1. Respiratory control ratio
2. When ATP is low (ADP is high), oxygen is slowly consumed because ATP is plentiful. As ATP gets consumed and ADP concentration becomes high, oxygen gets consumed at a higher rate to drive the synthesis of more ATP |
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Term
| What are the effects of Oligomycin and DNP? |
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Definition
Oligomycin - Prevents ATP synthetas from turning ADP into ATP
DNP - Allows H+ to flow down its gradient without driving ATP synthesis |
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Term
| Give an example of uncoupling and its use in thermogenesis |
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Definition
| UCP (uncoupling protein) in adipose tissue allows protons to leak through the inner membrane but generates heat in the process, allowing a non-shivering source of heat production |
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Term
| What is the main cause of radical oxygen species? |
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Definition
| Coenzyme Q donates its electron directly to oxygen instead of complex 3 |
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Term
| What are the 3 main reactive oxygen species? |
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Definition
| superoxide, hydrogen peroxide, and hydroxyl radical |
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Term
| What enzymes deal with radical oxygen species and which ones does each address? |
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Definition
Mn SOD - superoxide
Cu-ZN SOD - superoxide
Catalase - hydrogen peroxide
Glutathione peroxidase - hydrogen peroxide
Note: There is no known enzyme to address the hydroxyl radical. |
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