The History of Life on Earth<br />AP Chapter 25<br />
Figure 26.0  A painting of early Earth showing volcanic activity and photosynthetic prokaryotes in dense mats<br />
Overview: Lost Worlds<br />Past organisms were very different from those now alive<br />The fossil record shows macroevolu...
Fig. 25-1<br />
Fig 25-UN1<br />Cryolophosaurus<br />
The Age of the Earth<br />          4.6 billion years<br />
Figure 26.2  Clock analogy for some key events in evolutionary history<br />
3.9 billion years ago<br />Earth cooled, oceans formed, atmosphere contained nitrogen, CO2, methane CH4, ammonia NH3, and ...
Other ideas<br />Submerged volcanoes, deep-sea vents <br />Carbonaeceouschondrites found in meteorites contain C compounds...
All of these point to the possibility of an abiotic synthesis of life.<br />Life requires:<br />      accurate replication...
Fig. 25-3<br />20 µm<br />Glucose-phosphate<br />Glucose-phosphate<br />Phosphatase<br />Starch<br />Amylase<br />Phosphat...
First replicating molecule…<br />RNA<br />Why – capable of copying itself using ribozymes – enzyme-like RNA catalysts<br /...
Figure 26.11  Abiotic replication of RNA<br />
How is the age of fossils and rocks determined?<br />Radiometric dating – using half-lives of radioactive isotopes<br />Ca...
3.5 billion yearsFirst Single-Celled Organism<br />Oldest known fossils are stromatolites, rocklike layers of prokaryotes ...
Figure 26.3  Early (left) and modern (right) prokaryotes<br />
2.7 billion years agoOxygen<br />   Evidence of oxygen accumulation from cyanobacteria in banded iron formations<br />
2.1 billion years agoeukaryotic cells<br />Fossils of eukaryotic cells<br />Mitochondria and chloroplasts may have origina...
1.5 billion years agoMulticellular organisms<br />Oldest known fossils are algae<br />Severe ice ages (Snowball Earth) pre...
535 – 525 Cambrian Explosion<br />Great diversity of all types of eukaryotes<br />
500 myaMovement onto Land<br />Evolved adaptations to live on land and prevent dehydration<br />Plants and fungi colonized...
250 myaFormation of Pangaea<br />Destroyed and altered habitats, changed climates, created geographic isolation<br />
Mass Extinctions<br />There have at least 5 mass extinctions.<br />Permian – 250 mya, over 90% of marine and terrestrial s...
Mass extinctions provide many habitats and available niches to organisms that survive which leads to adaptive radiation.<b...
Evolution is not goal-oriented!<br />Often very complex organs have evolved gradually from simpler structures, such as eye...
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Chapter 25 (Class)

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Chapter 25 (Class)

  1. 1. The History of Life on Earth<br />AP Chapter 25<br />
  2. 2. Figure 26.0 A painting of early Earth showing volcanic activity and photosynthetic prokaryotes in dense mats<br />
  3. 3. Overview: Lost Worlds<br />Past organisms were very different from those now alive<br />The fossil record shows macroevolutionary changes over large time scales including<br />The emergence of terrestrial vertebrates <br />The origin of photosynthesis<br />Long-term impacts of mass extinctions<br />
  4. 4. Fig. 25-1<br />
  5. 5. Fig 25-UN1<br />Cryolophosaurus<br />
  6. 6. The Age of the Earth<br /> 4.6 billion years<br />
  7. 7. Figure 26.2 Clock analogy for some key events in evolutionary history<br />
  8. 8. 3.9 billion years ago<br />Earth cooled, oceans formed, atmosphere contained nitrogen, CO2, methane CH4, ammonia NH3, and water vapor<br />1920’s Oparin and Haldane hypothesized that under those conditions, organic molecules could be formed<br />1953 Miller and Urey performed an experiment and produced organic molecules<br />
  9. 9.
  10. 10. Other ideas<br />Submerged volcanoes, deep-sea vents <br />Carbonaeceouschondrites found in meteorites contain C compounds<br />Amino acid polymers from dripping organic monomers onto hot sand or clay<br />
  11. 11.
  12. 12. All of these point to the possibility of an abiotic synthesis of life.<br />Life requires:<br /> accurate replication and metabolism<br />Protobionts – collections of abiotically produced organic molecules surrounded by a membrane<br />Liposomes – evidence of this possibililty<br />
  13. 13. Fig. 25-3<br />20 µm<br />Glucose-phosphate<br />Glucose-phosphate<br />Phosphatase<br />Starch<br />Amylase<br />Phosphate<br />Maltose<br />(a) Simple reproduction by<br /> liposomes<br />Maltose<br />(b) Simple metabolism<br />
  14. 14. First replicating molecule…<br />RNA<br />Why – capable of copying itself using ribozymes – enzyme-like RNA catalysts<br />DNA would have replaced RNA as a better storage molecule<br />
  15. 15. Figure 26.11 Abiotic replication of RNA<br />
  16. 16. How is the age of fossils and rocks determined?<br />Radiometric dating – using half-lives of radioactive isotopes<br />Carbon-14 5,730 years<br />Also patterns of magnetic reversal of the earth is used<br />
  17. 17.
  18. 18. 3.5 billion yearsFirst Single-Celled Organism<br />Oldest known fossils are stromatolites, rocklike layers of prokaryotes and sediment.<br />
  19. 19. Figure 26.3 Early (left) and modern (right) prokaryotes<br />
  20. 20. 2.7 billion years agoOxygen<br /> Evidence of oxygen accumulation from cyanobacteria in banded iron formations<br />
  21. 21. 2.1 billion years agoeukaryotic cells<br />Fossils of eukaryotic cells<br />Mitochondria and chloroplasts may have originated as prokaryotes engulfed by other prokaryotes in endosymbiosis.<br />In serial endosymbiosis, mitochondria probably evolved first <br />
  22. 22.
  23. 23. 1.5 billion years agoMulticellular organisms<br />Oldest known fossils are algae<br />Severe ice ages (Snowball Earth) prevented diversity of eukaryotes for awhile<br />
  24. 24. 535 – 525 Cambrian Explosion<br />Great diversity of all types of eukaryotes<br />
  25. 25.
  26. 26. 500 myaMovement onto Land<br />Evolved adaptations to live on land and prevent dehydration<br />Plants and fungi colonized land together<br />
  27. 27. 250 myaFormation of Pangaea<br />Destroyed and altered habitats, changed climates, created geographic isolation<br />
  28. 28. Mass Extinctions<br />There have at least 5 mass extinctions.<br />Permian – 250 mya, over 90% of marine and terrestrial species disappeared; maybe due to volcanoes, Pangeae, glaciation<br />Cretaceous – 65 mya; ½ marine and many terrestrial forms, including dinosaurs; due to environmental changes or asteroidshitting the earth<br />
  29. 29. Mass extinctions provide many habitats and available niches to organisms that survive which leads to adaptive radiation.<br />For ex, mammals did not change much until the after 65 mya and the extinction of the dinosaurs. <br />
  30. 30. Evolution is not goal-oriented!<br />Often very complex organs have evolved gradually from simpler structures, such as eyes.<br />Evolutionary novelties may arise by modification of existing structures.<br />

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