prokaryotes_eukaryotes_web

prokaryotes_eukaryotes_web - How do we classify life on...

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How do we classify life on Earth? - More general question: how do we set up a classification scheme?
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Classification system: provides information helps us understand evolutionary relationships 1,400,000 named species
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Levels of a classification scheme Kingdom Phylum Class Order Family Genus species Taxonomic levels of increasing inclusiveness Hierarchical in nature Goal is to organize diversity of life in a way that is phylogenetically reasonable human construct.
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Fam Fam Fam Fam Fam Fam Fam Fam Fam Fam Fam Fam Fam Fam Fam Fam Fam Fam Fam Fam Fam Fam Fam Order Order Order Order Order Order Order Order Order Order Order Order Order Order Class Class Class Class Class Class Class Class ClassClass Class Phylum Phylum Phylum Phylum Phylum Phylum Kingdom G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G  ssssssss  ssssssssssss  ssssss  sssssssssssssssssssssssssssssssssss  sssssssssssssssssssssss  sssssssssssssssssssssssss  sssssssssssssss  ssssss
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The 5 Kingdoms Protists Monera Plants Fungi Animals Until very recently, most biologists used a 5 Kingdom system to classify living organisms. Traditionally, Kingdom was the highest taxonomic category. (Bacteria, Archaea) “Prokaryotes” “Eukaryotes” Fig. 26.15
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Fig. 26.10 - Campbell We will use a three-domain system
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Universal ancestor chemical evolution Bacteria Archaea Eukarya Molecular data indicates independent evolution of 3 lineages for 1.5+ billion years. see Fig. 27.2
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Fig. 27.12 A Simplified Phylogeny
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PROKARYOTES I. Domain BACTERIA II. Domain ARCHAEA - most are single-celled (although some occur in aggregations, colonies, or as very simple multicellular forms. Shapes: spheres = cocci, rods = bacilli, helices = spirochetes
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I. Domain Bacteria* A. Characteristics 1. small (1-5 μ m cells) 2. no nucleus 3. no organelles 4. cell wall of peptidoglycan 5. one RNA polymerase 6. circular chromosome 7. formyl-methionine initiator ( for start of protein synthesis; see page 317) 8. no introns 9. no histones associated w/ DNA *bacteria and cyanobacteria ("blue-green algae") see Table 27.2
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Image from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates A General Prokaryotic Cell http://gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookCELL1.html#terms
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Gram Positive Simpler cell wall A lot of peptidoglycan Antibiotics impair wall formation Gram stain can distinguish between 2 groups of bacteria – based on structure of the cell wall. Gram Negative More complex cell wall with less peptidoglycan More dangerous – less susceptible to antibiotics Grouping does not reflect evolutionary history often toxic Fig. 27.7 6 th edition See Fig. 27.3
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Many Bacteria can Move! Flagella
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This note was uploaded on 02/12/2009 for the course BIO 102 taught by Professor Bick during the Spring '09 term at Pace.

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prokaryotes_eukaryotes_web - How do we classify life on...

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