12. The Diversity of Life

12. The Diversity of Life - The diversity of life...

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The diversity of life Classification schemes - Diversity of life is overwhelming - Need some system to give order to this: Classification scheme: the method by which organisms are grouped, categorized, and named - how to categorize organisms to get the most information out of the name and organization? Binary naming system Binary naming system organisms have two-part names examples: humans (homo sapiens); canis familiaris (dog) - classification is hierarchial o higher order taxa contain lower levels higher levels inclusive of multiple lower levels o previously based on simple similarity o now tied to evolutionary history: descent from a common ancestor (homology) Linnaean system - 6 Kingdoms o phylum classes order
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o family genus species - K ing P hilip C ame O ver From G reece S aturday Examples Kingdom Animalia Phylum Chordata Class Mammalia Order Primata Family Hominidaae Genus Homo Species Homo sapiens Six Kingdoms/Three Domains - Kingdom : the highest classification level - Six Kingdoms were proposed - Comparison revealed to be very distinctive from the other four o Group the four together o The other two individually - Three domains now increasingly adopted o Taxonomic level ‘Domain’ placed above “Kingdom” - Now: Domain Kingdom Phylum Class Order Family Genus Species Three Domains Eukarya Animals, plants, fungi, protists
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Archaea Formerly kingdom Archaebacteria Bacteria Eukarya - Eukarya: all eukaryotes; includes animals, plants, fungi, and protists o Have membrane bound nucleus and endomembrane system o Complex intracellular organization Have many organelles o Eukaryotic ribosomes o Have standard membrane lipids (ester link) Archaea - Archaea: formerly archaebacteria o Often found in extreme environments o Membrane lipids with ether linkages o pseudopeptidoglycan cell wall o replication/gene expression more like eukaryotic Bacteria - bacteria: “standard” bacteria o have standard membrane lipids (ester link) o peptidoglycan cell wall o replication/gene expression bacterial o many are photosynthetic o some bacteria fix and recycle nitrogen
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o bacteria play key roles in carbon and sulfur cycles help erosion by releasing phosphorous and sulfur from soil Relationships among Domains (figure 26.7) - 3 Domains represent the oldest divergence in the history of life - Which occurred 1 st ? -
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This note was uploaded on 10/24/2011 for the course BIOL 110 taught by Professor Mason during the Fall '07 term at Purdue.

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12. The Diversity of Life - The diversity of life...

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