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

2. 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?

3. 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

4. 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)

6. 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).

7. 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

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

9. 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

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

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

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

13. 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.

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

15. chemosynthetic bacteria (extremophiles) Chemosynthesis:
02 + 4H2S + C 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)

16. Stromatolites
mostly cyano
Stromatolites from Shark’s Bay Australia

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