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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. The Gram Stain • Allows scientists to classify types of bacteria based on what the cell wall is made up of • Gram positive bacteria lack a cell wall and retain the stain appearing purple • Gram negative bacteria have a cell wall so do not take up the stain and appear pink

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

  16. Bacteria

  17. 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

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

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

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

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

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

  23. 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

  24. Viruses • Non-living particles composed of two main parts: • They cannot move or grow, and can only reproduce inside a host cell (No Kingdom affiliation) • Why do antibiotics not work to kill a virus? • How the Flu Virus invades a cell

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

  26. Protists • A eukaryote that is not a fungus, plant, or animal • Very diverse! • Can be plant-like, animal-like, and fungus-like • Example: African Sleeping Sickness caused by Trypanosoma • Video

  27. Fungi • Heterotrophic eukaryotes • Feed by absorption • Can be helpful – mushroom • Can be harmful – athelete’s foot, ringworm • Video: Penicillin

  28. Plants • Eukaryotes with cell walls • Carry out photosynthesis

  29. Animals • Multicellular, eukaryotic organisms that lack a cell wall • Two groups • Invertebrates – animals without a backbone • Vertebrates – animals with a backbone • Symmetry: • None • Radial: symmetrical around a central point • Bilateral: divided along a central plant

  30. Vertebrates • Order of evolution from earliest to most recent: Fish, Amphibians, Reptiles, Mammals

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