Evolution

1. Evolution D.1 Origin of Life on Earth

2. D.1.1 Describe four processes needed for the spontaneous origin of life on Earth • Synthesis of polymers from monomers • Self-replicating molecules • Synthesis of organic molecules • Water tends to depolymerize molecules (makes it difficult for molecules to become polymers) but is necessary for life

3. D.1.2 Outline the experiments of Miller and Urey into the origin of organic compounds • Simulated ‘pre-biotic’ Earth • Atmosphere made of H2O, H2, CH4, and NH3(like hypothesized for early Earth) • Successfully created major biomolecules

4. D.1.3 State that comets may have delivered organic compounds to Earth • Comets can carry organic compounds • Earth was bombarded with comets and asteroids 4 bya • Impact could help polymerize amino acids into polypeptides

5. D.1.4 Discuss possible locations where conditions would have allowed the synthesis of organic compounds • In space: • Scientists recreated environment that mimics space (low-pressure and low-temp) and synthesized amino acids • Support hypothesis that molecules needed for life could have originated in space (Panspermia)

6. D.1.4 Discuss possible locations where conditions would have allowed the synthesis of organic compounds 2. In alternating wet/dry conditions: • Seashore or flood plains of a river • Drying of clay particles could have catalyzed reactions to form early organic molecules • Evidence: Stromatolites (among oldest known fossils)

7. D.1.4 Discuss possible locations where conditions would have allowed the synthesis of organic compounds 3. Near Volcanoes: • Eruptions spit out water vapor, gases, and minerals which could form organic matter • Those raw materials plus the heat from volcano could have provided conditions to form amino acids and sugars

8. D.1.4 Discuss possible locations where conditions would have allowed the synthesis of organic compounds 4. In Deep Oceans: • Near thermal vents, hot water rises and picks up minerals along the way

9. D.1.5 Outline two properties of RNA that would have allowed it to play a role in the origin of life • RNA can self-replicate (w/o enzymes) • RNA can act as a catalyst (ribozyme) helping reactions

10. D.1.6 State that living cells may have been preceded by protobionts, with an internal chemical environment different from their surroundings • Protobionts are the evolutionary precursors of prokaryotic cells. • Protobionts may be originated as an array of microspheres (coacervates) of diverse organic and inorganic compounds enclosed by lipid membranes.

11. D.1.7 Outline the contribution of prokaryotes to the creation of an oxygen-rich atmosphere • About 3.5 bya, some bacteria developed the ability to photosynthesize • Helped convert iron dissolved in ocean water, into precipitates of iron oxide = rust-colored layers of rock • Waste production of photosynthesis is oxygen • Photosynthetic bacteria proliferated and produced more and more oxygen

12. D.1.8 Discuss the endosymbiotic theory for the origin of eukaryotes • See handout • Endosymbiosis involves engulfing and incorporating another cell