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EARLY EARTH and the ORIGIN OF LIFE

EARLY EARTH and the ORIGIN OF LIFE. Major Episodes. Isotopes of carbon. Life on Earth: 3.5-4.0 billion years Prokaryotes: 3.5 billion stromatolites Oxygen: 2.7 billion Cyanobacteria Eukaryotes: 2.1 billion Multicellular Eukaryotes: 1.2 billion Animal Diversity: Cambrian period

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EARLY EARTH and the ORIGIN OF LIFE

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  1. EARLY EARTH and the ORIGIN OF LIFE

  2. Major Episodes Isotopes of carbon

  3. Life on Earth: 3.5-4.0 billion years • Prokaryotes: 3.5 billion • stromatolites • Oxygen: 2.7 billion • Cyanobacteria • Eukaryotes: 2.1 billion • Multicellular Eukaryotes: 1.2 billion • Animal Diversity: Cambrian period • Land plants: 500 million

  4. Cambrian Explosion

  5. THE ORIGIN OF • LIFE • Spontaneous • generation • Biogenesis • Louis Pasteur

  6. Miller & Urey • Primitive • Atmosphere • H2O • H2 • CH4 • NH3 • Formation of organic monomers – first step in origin of life

  7. RNA may have been the first self replicating genetic material. • Replication & ribozymes (RNA autocatalytic) • Natural selection (genotype & phenotype)

  8. PROTOBIONTS – aggregates of abiotically produced molecules liposome

  9. RNA template for polypeptide formation Polypeptides act as primitive enzymes that aid replication of all RNA molecules, including competing RNAs

  10. FIVE KINGDOM SYSTEM

  11. Kingdom Characteristics – must know!

  12. PROKARYOTESAND THE ORIGINS OF METABOLIC DIVERSITY

  13. PROKARYOTES extremophiles eubacteria

  14. STRUCTURE & FUNCTION • Shape: cocci (spherical), bacilli (rod), spirilla (helical) • Diplo- (2), strepto- (chain), staphylo- (cluster) • Peptidoglycan (modified sugars cross-linked by short polypeptides) in cell walls • Gram stain: Gram+ (simpler walls, thick peptidoglycan) Gram- (more complex, less peptidoglycan) • Capsule: protective layer outside wall, sticky • Pili: surface appendages

  15. Motility: flagella, spirochetes (corkscrew,) slimy threads Taxis: movement toward or away from stimulus

  16. ORGANIZATION & REPRODUCTION • Specialized membranes • Nucleoid region • Plasmids* • Binary fission • Transformation • Conjugation • Transduction • Endospores • Antibiotics

  17. Nutritional Diversity: • Saprobes • Parasites • Metabolism of petroleum • Nonbiodegradable (synthetic organic compounds) Oxygen use: Obligate aerobes Facultative anaerobes Obligate anaerobes • Nitrogen Metabolism: • Nitrogen fixation • N2 NH4 • Cyanobacteria

  18. EXTREMOPHILES • Methanogens • Extreme halophiles (bacteriorhodopsin • Extreme thermophiles

  19. ECOLOGICALIMPACT • Decomposers • Symbiosis • Mutualism • Commensalism • Parasitism • Pathogenic • Koch’s Postulates • Exotoxins • Endotoxins • Bioremediation

  20. THE ORIGINS OFEUKARYOTIC DIVERSITY

  21. Characteristics • Eukaryotic, unicellular, colonial, multicellular • Nutrition: aerobic, photoautotrophs, heterotrophs, mixotrophs • Ingestive (protozoa), photosynthetic (algae), absorptive (fungus like) • Motility: flagella, cilia, psuedopodia • Life cycles: asexual (mitosis), sexual (meiosis & syngamy), cysts • Habitat: aquatic (plankton) & moist terrestrial areas, contractile vacuoles

  22. EUGLENA - MIXOTROPH

  23. EVOLUTIONARY TRENDS: 1) Filamentous Cyanobacteria – specialized cells 2) Complex communities –species w/ metabolic specialties 3) Compartmentalization within cells  eukaryotes ENDOSYMBIOSIS

  24. PRIMARY & SECONDARY ENDOSYMBIOSIS

  25. Diplomonadida and Parabasala lack mitochondria Giardia lamblia Trichomonas vaginalis

  26. Euglenozoa • both photosynthetic and heterotrophic flagellates Euglena - mixotrophic Trypanosoma – African sleeping sickness

  27. Alveolata • unicellular protists with subsurface cavities (alveoli) • Dinoflagellates: red tides (deadly toxins) Gonyaulax • Ciliates: paramecium, stentor • Apicomplexans: all parasitic, plasmodium - malaria

  28. Stramenopila • The stramenopile clade includes the water molds • and the heterokont algae Oomycota Water mold Diatoms: glass like cell walls Chrysophytes: Golden algae Phaeophytes: brown algae, Seaweeds (kelps)

  29. SEAWEEDS • Structural and biochemical adaptations help seaweeds survive and reproduce at the ocean’s margins • Food source, thickening agents, agar • Some algae have life cycles with alternating multicellular haploid and diploid generations

  30. Rhodophyta: Red algae lack flagella Most abundant large algae in warm coastal waters of tropical oceans

  31. Chlorophyta • Green algae and plants evolved from a common photoautotrophic ancestor • Unicellular (chlamydomonas), colonial (volvox), filamentous (spirogyra), multicellular (ulva) • Lichens

  32. A diversity of protists use pseudopodia for movement and feeding Rhizopoda: amoebas, amoebic dysentery

  33. Actinopoda (Heliozoan & Radiolarians) Foraminiferans calcium carbonate walls, limestone fossils, Dover cliffs

  34. Mycetozoa: Slime molds have structural adaptations and life cycles that enhance their ecological roles as decomposers 

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