10-22 - BIO 5099: Molecular Biology for Computer Scientists...

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BIO 5099: Molecular Biology for Computer Scientists (et al) Lecture 16: Eukaryotes at last! http://compbio.uchsc.edu/hunter/bio5099 Larry.Hunter@uchsc.edu Reminders about Eukaryotes Eukaryotes arose around the time of the oxygenation of the atmosphere. Time of radical change. Many pre-oxygen organisms went extinct, found anaerobic niches, or developed aerobic metabolisms Nearly all Eukaryotes contain mitochondria or chloroplasts. Cellular organelles which segregate energy production (and the required proton gradient) from the rest of the cell. Mitochondria and chloroplasts are themselves similar in many ways to bacteria (e.g. they have their own DNA) Mitochondria They resemble bacteria in size and shape, contain DNA, make protein, and divide by binary fission. They are the only place that respiration takes place in the Eukaryotic cell Almost all Eukaryotes without mitochondria (or chloroplasts) are obligatory anaerobes These Eukaryotes (e.g. microsporidia) split from the rest of the Eukaryotic tree very long ago. Exceptions (like Pelomyxa palustris ) has a symbiotic aerobic bacterium living in its cytoplasm.
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Origin of Eukaryotes Lynn Margulis proposed the symbiotic origin of eukaryotes theory in 1970 Highly controversial at the time, now widely accepted Key idea: Organelles (at least mitochondria) had free-living ancestors. Symbiosis Contemporary examples: Lichens: symbiotic association of algae and fungi Bacteria growing on a flagellate Results in coevolution and/or lateral transfer Mitochondria could have arisen from alpha-proteo bacteria Likely that few Eukaryotes without mitochondria lost them, rather than being similar to primitive proto- eukaryotes. Horizontal transmission makes the picture more complex
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Protists: Simple Eukaryotes Animals, Plants and Fungi are all Eukaryotes All Eukaryotes that are not the above are traditionally lumped together as protists. The Protists are then further grouped into
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This note was uploaded on 09/20/2011 for the course CSC BIO 5099 taught by Professor Prof.larryhunter during the Fall '02 term at University of Colorado Denver.

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10-22 - BIO 5099: Molecular Biology for Computer Scientists...

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