1. Primordial Earth Theories on the Origin of Life

2. Early Earth and Evolution A THEORY of the origins of the universe Big Bang When? -Approx. 13.5 Billion years ago expansion from singularity -MASSIVE AMOUNTS OF ENERGY! -Energy eventually converted to fundamental building blocks of matter. Evidence? -Expanding universe -Background radiation -Abundance of Hydrogen

3. After Big Bang……. Stars! –Need hydrogen gas  fusion –Form heavier elements –Really big stars go out with a bang  supernova! Planets! –Leftover “mess” from supernova start to accrete into larger objects. (NEWTONS LAW!) –Typically these objects will orbit around a star SOLAR SYSTEMS!

4. LIFE!!!! Spontaneous Generation. –Theory (hypothesis actually) that life can randomly emerge from non-living thing Biogenesis –Theory that life only comes from pre-existing life. Common Ancestor –Theory that every living organism on the planet is a descendent of an original cell Question : Where did first life come from???

5. Oparin-Haldane Hypothesis All the elements were already present on Earth. Early atmosphere contained mostly ammonia NH 3, hydrogen gas H 2, water H 2 O, and methane CH 4. High temperatures might cause gases to form simple organic compounds.

6. “Prebiotic Soup” As Earth cooled simple organic compounds collected in the lakes and seas. Energy from lightning and UV radiation caused chemical reactions to build macromolecules.

7. Key Experiments Francisco Redi’s Flies – –Where do maggots come from –Bottom Line: no spontaneous generation

8. Key Experiments Spallanzani – –Bacteria in broth come from air? Or other microbes? –Bottom Line: no spontaneous generation

9. Key Experiments Louis Pasteur – –Bacteria in broth come from air? Or other microbes? –Key difference from spallanzani? –Bottom Line: no spontaneous generation

10. 1953: Miller- Urey Stanley Miller and Harold Urey set up an apparatus to simulate the proposed primordial Earth conditions.

12. 1953: Miller- Urey Stanley Miller and Harold Urey set up an apparatus to simulate the proposed primordial Earth conditions. Found organic compounds.

13. Debatable points: Atmosphere probably contained CO, CO 2, and N 2 Presence of O 2, and CO 2 interfere with production of organic compounds. –Organic compounds produced in undersea volcanoes. Organic compounds came from outer space.

14. Pre-Cell Structures Organic molecules aggregate spontaneously. Microsphere: Protein membrane structure Coacervates: Droplets of lipids amino acids, and sugars.

15. Microspheres Coacervates

16. First Cells: Prokaryotic Environment: Little or no oxygen  Cells were anaerobic. Environment: Organic food molecules  Cells were heterotrophs. Oldest fossils look like prokaryotes.  Cells were prokaryotes.

17. Archaea Present day cells, thought to be similar to earliest cells. Unicellular organisms that thrive in harsh environmental conditions. –Anaerobic metabolism. –Inorganic energy sources.

19. Endosymbiotic Theory Creating the first eukaryotes: Large prokaryotes engulfed smaller prokaryotes. Mutually beneficial relationship: small cells are protected and large cell gets energy.

20. Small aerobic cells evolved into Small photosynthetic cells evolve into Mitochondria and chloroplast have their own DNA. DNA is circular, like prokaryotes. Replicate independently of cell. http://www.youtube.com/watch?v=dSjg_uYS_QY&feature=related chloroplast. mitochondria

21. Summary 1.Small organic molecules were synthesized. 2.Small organic molecules (monomers) joined to form polymers, like protein and nucleic acids. 3.Molecules could self-replicate. 4.Molecules were packaged into membrane structures- resembling the first prokaryotic cell.