1. THE HISTORY OF LIFE ON EARTH PART 1 UNIVERSE TO EUKARYOTES

2. BANG!!!! The universe was formed about 13.8 billion years ago (13,800,000,000)

3. Five billion years ago… Our solar system was a cloud of condensed matter Center collapsed  sun Further out aggregations  planets First two planets were too hot Fourth planet was too cold Third planet was just right!

5. PREBIOTIC EVOLUTION: requirements for life? Building blocks (compounds) Water Energy No oxygen gas

6. DNA or Proteins, Chicken or the Egg? DNA required to build proteins Proteins build DNA WHICH CAME FIRST? Think-pair-share

7. Maybe NEITHER? RNA – FIRST SELF-REPLICATING MOLECULE ? Ribozymes RNA molecules that act as enzymes Cut apart RNA Make more RNA Perhaps ribozymes randomly mutated and produced enzymes, which produced DNA RNA  PROTEINS  DNA

8. VIRUSES Nucleic acids Protective protein capsule NOTE: viruses could not have evolved at this point in time because they require host cell to reproduce. The building blocks require would merely have been available at this point in time.

9. Virus notes

10. THE AGE OF MICROBES 3.5 BILLION YEARS AGO  500 MILLION YEARS AGO

11. ORIGIN OF LIFE 1800’s prevailing theory: SPONTANEOUS GENERATION New life appears from non-living matter 1920-1930’s Poarin & Haldane proposed PREBIOTIC EVOLUTION Life arose from non-living matter through ordinary chemical reactions Recently: PANSPERMIA THEORY Organic building blocks (or possible even living organisms) were deposited on Earth by meteorites

12. 3.5 BYA, the Earth looked very different Earth began to cool, forming a stable crust Water vapour fell to Earth, creating oceans Atmosphere was filled with ammonia and methane, with no free oxygen Hydrothermal vents provided energy EXTREMOPHILES aka Archaea (and certain Bacteria)

13. Archaea notes

14. PROKARYOTES 3.5 BYA Archaea and Bacteria using anaerobic respiration consumed the energy molecules CO 2 and H 2 O remained, led the evolution of PHOTOSYNTHESIS Photosynthesis produces O 2 as waste, began to build up in the atmosphere 2 BYA Aerobic metabolism evolved Releases more energy than anaerobic

15. Anaerobic bacteria/Archaea Use up energy molecules in soup Photosynthetic bacteria Build up of oxygen in the atmosphere Aerobic bacteria

16. Bacteria Notes

17. EUKARYOTES Primitive predatory bacteria appeared next that could not photosynthesize or undergo aerobic metabolism  engulfed bacteria and digested them 1.4 BYA a predatory bacteria gave rise to first Eukaryotic cell

18. ENDOSYMBIOTIC HYPOTHESIS Certain types of bacteria evolved into chloroplasts and mitochondria after they were engulfed by predatory bacteria Nucleus is more obscure, but perhaps originated by in folding of cell membrane to protect the genetic material

19. Protista notes