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Evolutionary Tree of Life: Evidence from Fossils, Genetics, and Physiology

Explore the evolution of life on Earth through evidence from fossils, genetics, and physiology. Learn about the classification of organisms, including the 5 Kingdoms and 3 Domains, and understand the importance of bacteria in various ecosystems.

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Evolutionary Tree of Life: Evidence from Fossils, Genetics, and Physiology

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  1. Bacteria Archae- bacteria Protista Plantae Fungi Animalia 0 Cenozoic Colonization of land by animals Mesozoic Paleozoic 500 Appearance of animals and land plants First multicellular organisms 1000 PROTEROZOIC Oldest definite fossils of eukaryotes 1500 2000 Appearance of oxygen in atmosphere PRECAMBRIAN Millions of years ago Oldest definite fossils of prokaryotes 2500 3000 ARCHEAN 3500 Molten-hot surface of earth becomes cooler 4000 4500 Formation of earth The evolutionary tree of life can be documented with evidence. • Fossils • Genetics • Physiology

  2. Eukaryote Prokaryote Archaebacteria&Bacteria Classification • Old 5 Kingdom system • Monera • Protists • Plants • Fungi • Animals

  3. Classifying Life • Molecular datachallenges 5 Kingdoms • Monera was too diverse • 2 distinct lineages of prokaryotes • Protists are still too diverse • not yet sorted out

  4. 3 Domain system • Domains = “Super” Kingdoms • Bacteria • Archaea • extremophiles = live in extreme environments • methanogens • halogens • thermophiles • Eukarya • eukaryotes • protists • fungi • plants • animals

  5. KingdomBacteria KingdomArchaebacteria KingdomProtista KingdomFungi KingdomPlantae KingdomAnimalia

  6. Domain Bacteria Domain Archaea Domain Eukarya Common ancestor Prokaryotes Domain Bacteria Domain Archaebacteria

  7. Bacteria live EVERYWHERE! • Bacteria live in all ecosystems • on plants & animals • in plants & animals • in the soil • in depths of the oceans • in extreme cold • in extreme hot • in extreme salt • on the living • on the dead

  8. Bacterial diversity rods and spheres and spirals… Oh My!

  9. eukaryote cell prokaryotecell Prokaryote Structure • Unicellular • bacilli, cocci, spirilli • Size • 1/10 size of eukaryote cell • 1 micron (1um) • Internal structure • no internal compartments • no membrane-bound organelles • only ribosomes • circular, naked DNA • not wrapped around proteins

  10. Variations in Cell Interior cyanobacterium(photosythetic) bacterium aerobic bacterium internal membranesfor respirationlike a mitochondrion(cristae) internal membranesfor photosynthesislike a chloroplast(thylakoids)

  11. outer membrane of lipopolysaccharides Gram-negative bacteria Gram-positive bacteria peptide side chains outer membrane cell wall peptidoglycan cell wall peptidoglycan plasma membrane plasma membrane protein Prokaryote Cell Wall Structure peptidoglycan = polysaccharides + amino acid chains lipopolysaccharides = lipids + polysaccharides

  12. Prokaryotic metabolism • How do bacteria acquire their energy & nutrients? • photoautotrophs • photosynthetic bacteria • chemoautotrophs • oxidize inorganic compounds • nitrogen, sulfur, hydrogen… • heterotrophs • live on plant & animal matter • decomposers & pathogens

  13. Genetic variation in bacteria • Mutations • bacteria can reproduce every 20 minutes • binary fission • error rate in copying DNA • 1 in every 200 bacteria has a mutation • Genetic recombination • bacteria swap genes • plasmids • small supplemental circles of DNA

  14. Genetic variation in bacteria Transformation • Taking in DNA from the environment • Cell surface receptors recognize closely related DNA and take it in! Griffith experiment, showing genetic material could be transferred

  15. Genetic variation in bacteria • Transduction • Bacteriophages • Specialized viruses that infect bacteria only • Take DNA from one bacteria to another • Like a mosquito carrying a parasite

  16. Genetic variation in bacteria Conjugation • Two bacteria are temporarily joined by a pilus • One way only

  17. Bacteria as pathogens • Disease-causing microbes • plant diseases • wilts, fruit rot, blights • animal diseases • tooth decay, ulcers • anthrax, botulism • plague, leprosy, “flesh-eating” disease • STDs: gonorrhea, chlamydia • typhoid, cholera • TB, pneumonia • lyme disease

  18. Bacteria as beneficial (& necessary) • Life on Earth is dependent on bacteria • decomposers • recycling of nutrients from dead to living • nitrogen fixation • only organisms that can fix N from atmosphere • needed for synthesis of proteins & nucleic acids • plant root nodules • help in digestion (E. coli) • digest cellulose for herbivores • cellulase enzyme • produce vitamins K & B12 for humans • produce foods & medicines • from yogurt to insulin

  19. Any Questions??

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