BIOL 204 Lecture Notes - Lecture 35: Superoxide Dismutase, Electron Acceptor, Cytochrome C Oxidase
4 Apr 2018
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E. coli, lactobacillus (produces yogurt), s. cerevisiae (yeast in brewing/baking: 3) strict aerobes, have absolute requirement for oxygen to survive, unable to live solely by fermentation, ex. Paradox of aerobic life: many organisms cannot exist without oxygen because it is required for electron transport, but oxygen itself is dangerous to all forms of life. Takes 4 electrons to completely reduce a molecule of o2 to h2o. Partially reduced forms of o2 are formed when o2 accepts fewer number of electrons producing ros (reactive oxygen species: ex. Superoxide and hydrogen peroxide: ros are strong oxidizing agents, can remove electrons from proteins, lipids, dna, result in damage, if ros levels are excessive results in cell death. Aerobic cells contain enzymes superoxide dismutase (sod) and catalase that convert superoxide and hydrogen peroxide to water. Cells have antioxidants (vit c/vit e) which are reducing agents that reduce. Excessive ros build up can lead to parkinson, alzheimer, dementia, aging.
