Lecture_7_Prokaryotes

Lecture_7_Prokaryotes - 6/15/2011 Five kingdoms vs. Three...

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6/15/2011 1 Prokaryotes LS1: Summer Session A July 6, 2011 Five kingdoms vs. Three domains You may have learned that all of life can be classified into 5 kingdoms Monera Protista Fungi Plantae Animalia Robert Whittaker (1920-1980) Five kingdoms vs. Three domains New evidence suggests that the Monerans are exceedingly diverse Led to a revision in the classification system Carl Woese (1928 - ) What are the similarities? All three Domains: Conduct glycolysis Possess DNA Have the same genetic code Plasma membranes Abundant ribosomes Prokaryotes Bacteria and Archaea Differences between the three domains of life
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6/15/2011 2 The prokaryotic cell is simple and small Comparison between Bacteria and Archaea Bacteria Cell wall composed of peptidoglycan Plasma membrane similar to eukaryotes Distinct ribosomes and RNA polymerase, but protein synthesis similar to eukaryotes Archaea Cell wall composed of unique polysaccharides Plasma membranes unique Ribosomes similar to eukaryotes, but protein synthesis a mix between bacterial and eukaryotic systems Bacterial Morphology (Yawn) Spherical: cocci Rod-like: bacilli Spiral: vibrios (curved) and spirilla (helix) Metabolic diversity Metabolism involves carbon and energy Carbon sources Autotrophs Use carbon dioxide as their carbon source Heterotrophs Obtain carbon from organic molecules Energy Chemotrophs Obtain energy by oxidizing inorganic or organic substances Phototrophs Use light as energy source Prokaryotes exhibit every possible combination Metabolic diversity Some prokaryotes live without the presence of oxygen Obligate anaerobes are those organisms that cannot tolerate the presence of oxygen Facultative anaerobes can shift between aerobic and anaerobic modes Aerotolerant anaerobes do not utilize oxygen, but are not damaged by it Other prokaryotes require the presence of oxygen ( obligate aerobes )
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6/15/2011 3 Metabolic diversity Nitrogen metabolism Denitrifiers use nitrate (NO 3 - ) in cellular respiration as the final electron acceptor in lieu of
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Lecture_7_Prokaryotes - 6/15/2011 Five kingdoms vs. Three...

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