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Chapters 18 and 19

Chapters 18 and 19. Classification and the Tree of Life. Systematics. The scientific way of organizing and naming living things Dichotomous keys are used for identification purposes Based on physical traits. Cladograms.

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Chapters 18 and 19

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  1. Chapters 18 and 19 Classification and the Tree of Life

  2. Systematics • The scientific way of organizing and naming living things • Dichotomous keys are used for identification purposes • Based on physical traits

  3. Cladograms • Cladograms are diagrams the depict the pattern of shared characters, either derived characters or primitive characters • Primative: characteristic shared by all organisms in the cladogram (Vert. Column • Derived: trait that arose in the most recent common ancestor • Based on DNA, skeletal, and comparisons

  4. Cladograms • Clade: Consists of a single common ancestor and all the groups that descended from that ancestor • Organism A,B,C are all related because they are in the same Clade • Organisms B and C are more closely related than B and A because organisms B and C share a common trait • Node: Point where two groups branch off from each other

  5. Cladogram • Which traits does a lizard and a salamander share? • Which two organisms are most closely related? • What trait does a human have that gorilla does not?

  6. Phylogeny & Systematics • Carolus Linnaeus first to assign each species a two-part latinized name called binomial nomenclature (Genus species) • Ex: Homo sapians

  7. Phylogeny & Systematics • Phylogenetic trees show the relationship between classification and phylogeny • Year 2525 Activity

  8. Old way 5 Kingdoms – Bacteria grouped into one kingdom called Monera

  9. New way • 6 Kingdoms • Eubacteria* • Achaebacteria* • Plantae • Animalia • Fungi • Protista 3 Domains: Bacteria, Achaea, and Eukarya (Plantae, Animalia, Fungi, and Protista)

  10. Bacteria vs. Archaea • The first two of the 3 domain system • Kingdom Bacteria (Eubacteria) • Kingdom Archaeabacteria • Both are unicellular and prokaryotic

  11. Bacteria • Bacteria are classified by shape: • Spheres are cocci –us • Rods are bacilli –us • Curves or spirals are spirilli -um

  12. Eubacteria • Free living or parasitic • Unicellular • As a group they exhibit much more nutrition diversity than eukaryotes, ex: cyanobacteria

  13. Archaeabacteria • They are the oldest life-forms & remain the most numerous & widespread organisms • Unicellular or multicellular • Archaea are extremeophiles • Halophiles – salt loving • Thermophiles – hot vents • Methanogens – gassy areas

  14. Reproduction • Reproduce via binary fission or conjugation • Binary Fission = form of asexual reproduction • Conjugation = Transfer of genetic material by cell to cell contact

  15. Bacteria

  16. Bacteria • External Structures: • Capsule - the cell wall is covered in a sticky capsule, this slime layer helps to evade the immune system & adhere to surfaces

  17. Bacteria • External Structures: • Pili - used to stick to their substrate, hair-like projections, & can be used for the exchange of genetic material (sex pili)

  18. Bacteria • External Structures: • Flagella - enable bacteria to move, embedded in the cell membrane & cell wall • Other forms of motility include chemotaxis, phototaxis & magnetotaxis

  19. Bacteria • Internal Structures: • Endospores - some prokaryotes can withstand harsh conditions by remaining dormant, until conditions become favorable; just encloses the DNA

  20. Bacteria • Some bacteria cause disease, called pathogenic bacteria • They can release exotoxins or endotoxins

  21. Bacteria • Bacteria can be used as biological weapons • Ex: anthrax

  22. Bacteria • Prokaryotes help recycle chemicals, dead and decaying materials and they can help clean the environment • Examples of bioremediation: sewage treatment facilities, oil spills & toxic mine wastes

  23. Viruses • Non-living particles composed of two main parts: • Nucleic Acids (DNA or RNA) • Protein Coat (capsid) • No membranes, cytoplasm, ribosomes or other organelles • They cannot move or grow, and can only reproduce inside a host cell (No Kingdom affiliation) • Extremely small and only visible with advanced electron microscopes

  24. Viruses • Human Examples: • Chickenpox • Smallpox • Rabies • AIDS • Cancers • Hepatitis • Influenza A, B & C

  25. Bacteriophages • Bacteriophage • Virus that infects bacterial cells • Structure: Head (Capsid), DNA, Tail & Tail Fibers

  26. Life Cycle of a Virus • DNA or RNA injected into host • Replication, transcription, and translation occurs • Cell bursts and new bacteriophages emerge • **Kills host cell** • DNA or RNA injected into host • Prophage is made = cell DNA + bacterial DNA • Virus can be released or remain within host cell • **Coexists within host cell** LYTIC CYCLE LYSOGENIC CYCLE

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