1. Earth’s Atmosphere & The Origin of Life

2. Stages of Earth’s Atmosphere
Reducing Atmosphere
Neutral Atmosphere
Oxidizing Atmosphere

3. Reducing Atmosphere Major Gases
Hydrogen (very reactive) and subsequently Methane, Ammonia, Hydrogen Sulfide, and Water Vapor

4. Important Reactions H2 + Oxygen Comp.  Water
H2 + Nitrogen Comp.  Ammonia (NH3)
H2 + Carbon Comp.  Methane (CH4)
H2 + Sulfur Comp.  Hydrogen Sulfide (H2S)

5. Stanley Miller’s Experiment

6. Origin of Organic Molecules
Stanley Miller demonstrated that Earth’s earliest atmosphere could produce some organic molecules arise from inorganic substances
Organic Molecules are complex compounds that contain Carbon and Hydrogen atoms

7. Neutral Atmosphere
Major Gases
Nitrogen, Carbon Dioxide, and Ozone

8. Important Reactions Photodissociation Reactions involving Oxygen
H2O with UV radiation  H2 + O2
Oxygen Gas  Ozone (O3)
Reactions involving Oxygen
O2 + NH3  Nitrogen Gas (N2) + H20
O2 + CH4  Carbon Dioxide (CO2) + H20
(Greenhouse Effect)

9. Origin of Life

10. The Cell The cell is a place where chemical reactions occur.
The container is composed of phospholipids having hydrophilic heads and hydrophobic tails.

11. Oxidizing Atmosphere Major Gases Evolution of Eukaryotic Cells
Nitrogen, Carbon Dioxide, Oxygen, Ozone
Evolution of Eukaryotic Cells

12. Endosymbiont Hypothesis
Eukaryotic cells containing
a nucleus and membrane
bound organelles
(Chloroplasts and
Mitochondria) are believed
to have arisen from
Prokaryotes that
incorporated other
Prokaryotes.