7 - endosybiosis - chloroplasts - electron transport

7 - endosybiosis - chloroplasts - electron transport - BME...

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BME 418, Quantitative Cell Biology Alan J. Hunt 7 - Mitochondria, Chemiosmotic hypothesis, Electron Transport in Choroplasts "Endosymbiont" theory (from "symbiosis"): - Double membrane structure (draw) suggests possible swallowing of one membranated structure into another - Both chloroplasts and mitochondria contain their own circular DNA, RNA and ribosomes (all are more similar to prokaryotic cells than the equivalent nuclear elements). This led to the proposal of endosymbiotic theory for the origin of eukaryotes, which was most thoroughly developed by Lynn Margulis. According to this theory, a critical step in the evolution of eukaryotes was the internalization of one single-celled organism by another. This arrangement, which presumably developed as a relationship mutually beneficial to both organisms, eventually became permanent, and the internalized organism and it's host became increasingly interdependent until they were no longer what we would consider separate organisms. Is this a plausible theory? There are many examples of organisms that have obligate dependence on each other for survival. Lichens are a commonplace example. An especially illustrative example of interdependence can be found in the gut of certain Australian termites. Termites accomplish an exceptional feat in that they can digest wood. This requires cellulose to be broken down, which is difficult both chemically and mechanically. Strictly speaking termites cannot digest cellulose, they rely on an
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This note was uploaded on 03/02/2009 for the course BIOMEDE 418 taught by Professor Hunt during the Winter '08 term at University of Michigan.

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7 - endosybiosis - chloroplasts - electron transport - BME...

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