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Explore the Five-Kingdom System, Binomial Nomenclature, and Phylogeny to classify organisms and study evolutionary history. Learn about the levels of classification, domains, and naming conventions in the world of biology. 8 Relevant
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The Five-Kingdom System a.k.a. - prokaryotes
Binomial Nomenclature • 2 Part Latin names for living things • ‘Scientific Names’ • Genus + Species • Ex/ Homo sapiens • We generally use a dichotomous key to name organisms Carolus Linnaeus (1707-1778)
Binomial Nomenclature (cont’d) • Back then the Earth was flat, and living things did not evolve… • Now we use PHYLOGENY in combination with old knowledge to study evolutionary history
3 Domains – Based on Evolution Common Ancestor - ~3.7 Billion Years Ago
Classification of Bacteria • Light microscope was the original tool • Initial classification was based on of the shape of the bacterial cells • Cocci • Bacilli • Spirilla • Spirochetes
Taxonomy / Systematics • Identification • Distinguishing features • Engine size • Mileage • Number of passengers • Type of transmission • Classification • Organization into groups • Car • Truck • SUV • Van • Nomenclature • Providing a formal name • Genus & species • Ford Crown Victoria • Chevy Impala • Toyota Camry • Honda Civic Consistent rules for all Scientists Relevant Meaningful Make biological sense Evolutionary context
Domains can be Divided into Many Sub-classifications • Domain: Bacteria • Phylum: Proteobacteria • Class: Gamma Proteobacteria • Order: Enterobacteriales • Family: Enterobacteriaceae • Genus: Escherichia • Species: Escherichiacoli
Binomial nomenclature • Genus & species • Escherichia coli • Genus name is always capitalized • Species name is never capitalized coli • Both names are always either italicized or underlined • Abbreviation: E. coli
Old School Medical Microbiologists said… • One bacterium = One disease • So to these scientists, bacteria were also classified as to the disease they caused • But there are several types of E. coli… • So the naming system for bacteria evolved
Extra Stuff for Naming Bacteria • strain or variety – a culture derived from a single parent that differs in structure or metabolism from other cultures of that species • type – a subspecies that can show differences in antigenic makeup ,susceptibility to bacterial viruses, and in pathogenicity • Four Groups Based on Cell Wall Composition • Gram-positive cells • Gram-negative cells • Bacteria without cell walls • Bacteria with chemically unique cell walls