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15 Cards in this Set
- Front
- Back
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What does ROS damage to lipids cause?
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Arthrosclorsis
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What does ROS damage to DNA cause?
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Cancer
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In nature how does O-O naturally exist?
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NOT O=O
Actuallly O-O each oxygen with an unpaired electron (biradical) spinning in the SAME direction. This causes oxygen to not be able to add effectively to other bonds so oxidation is spontaneous but now sudden. |
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What are 2 ways that ROS are produced from H2O2?
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-H2O2 + superoxide = hydroxyl radical
-H2O2 + e- (from Fe2+ -> Fe3+) = hydroxyl radical |
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Besides H2O2, where else can a ROS come from?
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When e- is transferred in the ETC from CoQH to CoQ, it can occasionally escape.
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How does ionizing radiation form a ROS?
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H2O + ionixing radiation = hydroxyl radical + hydrogen atom.
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How do ROS damage lipid membranes?
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-Chain reaction
-Makes membranes more hydrophilic -Free radical usually attacks the carbon next to a C=C. |
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How do ROS damage DNA?
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-Guanine + hydroxyl radical = 8-hydroxyguanine.
-8-hydroxyguanine pairs with A, not C, and causes non conservative changes |
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Nitric oxide can also be a free radical. What is the important structure that it can form?
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Peroxynitrite, which is a strong oxidizing agent.
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The body can also use ROS as protection against bacteria. What are two pathways, starting with H2O2?
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-Add Cl- to form HOCL (bleach)
-Create hydroxyl radical with extra e- from Fe2+ to kill bacteria. |
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What are several protections that the body has against ROS?
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-Catalase takes out H2O2
-Superoxide dismutase takes out superoxide -Fe2+ is sequestered in ferritin -Mitochondria and peroxisomes (potentially sources of ROS are compartmentalized) |
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What does superoxide dismutase (SOD) form O2- (superoxide) into?
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O2 and H2O2
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What disease is caused by a mutation in the gene encoding for SOD1 (superoxide dismutase)?
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Lou Gehrig's or Amyotrophic Lateral Sclerosis
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What is the mechanism by which SOD disables superoxide?
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Two step process:
-The oxidized enzyme is reduced by absorbing the unpaired electron from a superoxide and converts it into O2 -The reduced enzyme forms H2O2 from ANOTHER superoxide + 2H+ and becomes oxidized again for another round. Net: 2 superoxides +2H+ = O2 and H2O2 |
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What is the net reaction for catalase disabling H2O2?
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2H2O2 = 2H2O + O2
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