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6 Cards in this Set
- Front
- Back
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The Paradox of Aerobic Life
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Many anaerobic prokaryotes die in the presence of oxygen
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Reactive Oxygen Species
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The reaction of oxygen to water is a four electron reduction
If oxygen receives one electron at a time in a stepwise fashion it leads to partially reduced forms of oxygen which are highly reactive ROS are strong oxidizing agents and can damage biological molecules |
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ROS and Aerobic Species
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Aerobic species contain enzymes :
1) Superoxide dismutase: Rapidly converts superoxide into hydrogen peroxide so it doesent sit around for long 2)Catalase: Take hydrogen peroxide and rapidly converts it into a hydroxyl radical Anaerobic species die in oxygen because they lack one or more of these enzymes |
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The Role of Cytochrome Oxidase in the Production of ROS
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Cytochrome Oxidase: The last enzyme of the mitochondrial ETC that donates electrons from the carrier cytochrome to oxygen
However, it does this in a way that leads to no ROS degeneration The enzymes contains four redox centers, each of which can store a single electron When all centres are reduced, the enzyme transfers all four electrons to an oxygen molecule, producing two molecules of water Cytochrome oxidase is the ONLY enzyme in all aerobic organisms used for electron transport, indicating the difficulty of carrying electrons to oxygen If the reaction resulted in significant ROS formation, aerobic life never would have formed |
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Human Diseases Linked to Mitochondrial Dysfunction
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Parkinsons Disease: Linked to complex 1(NADH dehydrogenase), it doesent work as well as normal
Anything that affects the efficiency of electron flow is going to cause a defect in producing oxygen |
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The Relationship between Oxygen and Glucose
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Adequate oxygen: Go into mitochondria to do krebs, oxidative phosphorylation, etc
Not enough oxygen: Stay outside of the mitochondria High levels of glucose: Stays in the cytosol, high levels of fermentation Low levels of glucose: High rates of ETC, oxidative phosphorylations, ATP etc **Under caloric restriction, all the carbon is going onto the mitochondria with high rates of everything IN ANIMALS High levels of glucose in our cells causes diversion at Acetyl CoA to produce carbohydrates, fats, which is lower levels of mitchondrial respiration |
