Origin of Life Just write the red lettering into your notebook.

Happy Monday! Please take out your notebooks (or a piece of paper) and a pencil, then go place you backpacks on the table. Cell phones and headphones should be placed in you bag. Quietly begin your bell ringer in your notebook. Bellringer: There are many theories on how/why there is life on Earth. How do you think life came to be?

Origin of the Earth Universe formed 15 billion years ago (Big Bang) Galaxies formed from stars, dust and gas Earth formed 4.6 billion years ago

Origin of the Atmosphere Suns energy stripped away 1st atmosphere 2nd atmosphere formed from volcanic outgassing Primitive atmosphere: Mostly CO2, water vapor, No Oxygen, very hot, lots of lightning lesser amounts of CO, N2, H2, HCl, and traces of NH3 and CH4 (3.5 bya)

Formation of Earth’s Oceans (4 bybp): Oceans formed from off gassing of water vapor from volcanoes and meteorites with ice. Condensation Rain Early in Earth’s history, widespread volcanic activity released large amounts of water vapor (H2O vapor) and smaller quantities of other gases. As Earth cooled, the water vapor (a) condensed into clouds and (b) fell to Earth’s surface, where it accumulated to form the oceans (c).

Origin of Life Miller & Urey (1953)- Organic Molecule Theory - mixed water vapor, NH3, CH4, H2+ electric spark amino acids and other organic compounds electrodes spark CH4 NH3 H2 water vapor condenser boiling water water containing organic compounds

Origin of Life Produced: 20 amino acids Several sugars Lipids Purine and pyrimidine bases (found in DNA, RNA & ATP)

Origin of Life Life began~ 3.5 bya Organic molecules (C H O N P S) swimming in shallow seas Stage 1: Abiotic synthesis of organic molecules such as proteins, amino acids and nucleotides

Origin of Life Stage 2: joining of small molecules (monomers) into large molecules

Origin of Life Stage 3: origin of self-replicating molecules that eventually made inheritance possible

Origin of Life Stage 4: packaging these molecules into pre-cells, droplets of molecules with membranes that maintained an internal chemistry

Hydrothermal Vent Theory At the bottom of the ocean, chimneys of very hot material under immense pressure combined to make inorganic material that then formed into macromolecules and then life.

Meteorite Theory – Rocks containing bacteria and other organic molecules survived impact and seeded the planet with life.

chemosynthetic bacteria (extremophiles) Chemosynthesis: 02 + 4H2S + C02 CH20 + 4S +3H20 Stromatolites (bacteria & cyanobacteria) Oldest fossils found in western Australia and southern Africa ~ 3.5 byo Photosynthesis: 6H2O + 6CO2 + nutrients + light energy C6H12O6 + 6O2 Stromatolites are hard, sedimentary structure built by mat-forming microbial communties. They range in size from a few mm to hundreds of meters (most are < 1 m) They are rare today, being found in only a few inhospitable environments such as the geothermal pools in Yellowstone and hypersaline parts of Sharks Bay Stromatolites were more common in the proterozoic Their decline in abundance has been attributes to the effects of grazing by newly evolved metazoans (animals)

Stromatolites mostly cyano Stromatolites from Shark’s Bay Australia

Origin of the Atmosphere O2 came in 1.5 bya from photosynthesis Present atmosphere: 78% N2, 21% O2, 0.04% CO2, + trace gasses