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Ch. 18 Part 3 Classification and Biodiversity Classification • System for biologists to arrange organisms into groups • Categories = easier to remember • Taxonomy – Study and practice of classification • Involves placing organisms into a series of taxonomic units called TAXA which form a hierarchy • Each different organism is assigned a SPECIES – Similar species are grouped into the same GENUS » Similar GENERA (plural) are grouped into FAMILIES • Similar families are grouped into ORDERS • Similar orders are grouped into CLASSES • Similar classes are grouped into PHYLUMS • Similar phylum are grouped into KINGDOMS Largest hierarchy of classification is DOMAIN So how do we classify??? Domain - Eukarya Domains • Broadest category of classification • 1970’s • Scientists needed a new category to distinguish between extremophiles and normal bacteria • Three main domains – Domain Archaea: • unicellular prokaryotes that live in extreme environments (very hot or very cold, extremely acidic or basic) • Extremeophiles – Domain Bacteria: All other unicellular prokaryotes – Domain Eukarya: Organism made up of eukaryotic Cells • Includes 4 kingdoms: Protists, Fungi, Plants, Animals (and Monera) Still some confusion among scientists over this one… Domain Archaea • Extremophiles – Currently, there are some living in less extreme areas of the ocean • Prokaryotic • More in common with Domain Eukarya than – Genes coding for ribosomes very similar to those genes found in eukaryotes Domain Bacteria • • • • • • No nucleus Size similar to bacteria No membrane-bound organelles DNA is circular chromosome WITH histones present Contain Plasmids 70S ribosomes – Smaller than eukaryotes 80S ribosomes, BUT similar structure to eukaryotic ribosomes • • • • • Cell wall ALWAYS present (not made of peptidoglycan) Divides by BINARY FISSION Exist as single cells or groups of cells Similar metabolism to normal bacteria Transcription similar to eukaryotic transcription Consists of 1 MAJOR Kingdom • Archaeabacteria Domain Bacteria • Prokaryotic (no nucleus) • Small size 0.5 to 5 um in diameter – Range between largest virus and smalled eukaryote • DNA is circular chromosome with NO histones • Plasmids present • No membrane-bound organelles present • 70S ribosomes • Cell wall always present – Contains peptidoglycan NOT cellulose • Divides by binary fission • Exists as single cell or groups of cells Consists of 1 MAJOR Kingdom • Eubacteria Domain Eukarya • Cells contain a nucleus • Membrane-bound organelles • DNA arranged in LINEAR chromosomes WITH histones • 80S ribosomes – Mitochondria and chloroplasts 70S ribosomes • Chloroplast and mitochondrial DNA is circular • Great Diversity in how they exist – Unicellular – Colonial – multicellular • Cell division by MITOSIS • Asexual and Sexual reproduction Consists of 4 MAJOR Kingdoms • Protoctista • Fungi • Plantae • Animalia Kingdom Protoctista • Any eukaryote that is not fungi, plant, or animal • Consists of wide range of organisms – PROTOZOANS (simple animals) • Similar to animal cells • NO cell wall – ALGAE (seaweeds) • Similar to plant cells • Have cell wall and chloroplasts • Strong argument to classify these as PLANTS • Single-celled • Exists as single cell or group of cells Kingdom Fungi • All heterotrophic – Use organic compounds made by other organisms for energy source • Decomposers energy obtained from dead and decaying organism • Parasitic feed on host • Confused with plants b/c they are NONMOTILE • Wide range in size (some microscopic) • Eukaryotic • NO chlorophyll and do NOT use photosynthesis • Reproduce by SPORES • Simple body forms – Unicellular – HYPHAE long threads with or without cross walls • Compacted hypahe make up larger body forms like mushrooms • Contain cell walls made of CHITIN • NO cilia or flagella Kingdom Plantae • ALL multicellular – Differentiated tissues and organs • ALL photosynthetic (AUTOTROPHIC) • Eukaryotic (nucleus) • Complex bodies – Above ground – Branched • Few types of specialized cells • SOME cells have chloroplasts and use photosynthesis • Cells contain LARGE, permanent vacuoles for SUPPORT • Cell walls made of CELLULOSE May have flagella – Male gametes in some types of ferns Kingdom Animalia • Eukaryotic (nucleus) • ALWAYS MULTICELLULAR – Differentiated and specialized cells • Differentiated into tissues and organs • ALL Heterotrophic • Contain NERVOUS SYTSEM – Important in communication • Do NOT have chloroplasts and cannot use photosynthesis – Exception: some coral polyps with protoctists living in tissues • Small, temporary cell vacuoles (exocytotic vacuoles, food vacuoles, lysosomes)NO cell walls • Cells sometimes have cilia and flagella • • • • Microorganisms Range in size from 20-300 nm (50x smaller than average bacteria) Visible with electron microscope NO cell structure – No membrane – No cytoplasm – No ribosomes • Consist solely of: – Self-replicating DNA or RNA molecule – Protective coat of proteins • • • Capsid protein coat Capsomere proteins embedded in capsid When free in environment: – They are infectious – No metabolism • • • Must use machinery of host cells to copy their genetic material Use energy from host cell to do these things Taxonomic classification – Based on diseases that viruses cause – Type of genetic material they contain Viruses Types of Viruses Nucleic Acid DNA Number of Strands 1 2 Example Host Disease Canine parvirus type 2 Dogs Canine parvovirus African mosaic virus Cassava plants Mosaic virus Varicella zoster virus (VZV) Humans Chicken pox Rotavirus Humans Gastroenteritis Morbillivirus Humans Measles Tombaco mosaic virus (TMV) Tomato, tobacco, pepper Mosaic disease Humans HIV/AIDS 1 RNA 2