How life began
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How Life Began. 1. Physical and Chemical Characteristics. A. Early atmosphere was thicker with carbon dioxide and red in color. B. The ocean was olive in color C. Great Bombardment Asteroid/meteorite bombardment created harsh conditions.

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How Life Began

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How Life Began

1. Physical and Chemical Characteristics

  • A. Early atmosphere was thicker with carbon dioxide and red in color.

  • B. The ocean was olive in color

  • C. Great Bombardment Asteroid/meteorite bombardment created harsh conditions

2. Early Environment Survivor- Mexican Cave Analogy

Chemosynthetic bacteria: use Hydrogen Sulfide for energy source; survives in snotites or in phlemballs.

3. Carbon

  • A. Basis of living things.

  • B. Bonds to form diverse compounds.

  • C. Miller’s experiment- amino acids that contain carbon formed in harsh conditions similar to early Earth.

  • D. Old rocks in Greenland contain carbon.

4. Great Bombardment

  • A. Asteroid and comet bombardment

  • B. Tons of dust from the Universe bombards Earth.

  • C. Dust contains carbon, elements, compounds and minerals.

  • D. The building blocks of life, amino acids, form then peptides/protein.

  • E. Collision Simulation Experiment- amino acids survived force similar to comet impact and fused to form larger molecules or peptides.

5. Environments where life could be protected from great bombardment

  • A. Underground- microbes live in dark places and use chemicals like methane, propane, and ethane, for food and energy: chemosynthesis.

  • B. Deep ocean- microbes live on chemicals like Hydrogen Sulfide for food and energy: chemosynthesis.

Amino acids, peptides, and proteins

6. Environment less hostile due to decreased bombardment

  • A. Bacteria moved to shallow ocean and used Sun’s light energy, carbon dioxide and water to make food and release oxygen: photosyntheticbacteria.

  • B. Bacteria evidence found in stromatolites, the oldest fossils.

  • C. Cyanobacteria: first to use photosynthesis, releaseoxygen as a waste product.

  • D. Oxygen absorbed into oceans and combined with iron to form oxides.

  • E. Cyanobacteriastarts the increase of oxygen from 1% to 21% (today), allows diversity of life, forms O3 (ozone) which provides a protective layer vs. UV.



Iron ore

Order of Events of How Life Began

  • Solar Nebula

  • Accretion

  • Bombardment

  • Radioactive decay

  • Iron Catastrophe

  • Magnetic Field

  • Volcanoes

  • Plantesimal hits Earth- tilt

  • Moon moves away

  • Water on surface, crust forms

  • Great Bombardment

  • Chemosynthetic bacteria

  • Great bombardment ends

  • Photosynthetic bacteria form; cyanobacteria

Order of appearance of living things on Earth

  • 4 elements- C, O, N, H

  • Amino acids

  • Peptides

  • Proteins

  • Microbes-chemosynthetic

  • Cyanobacteria- photosynthetic

  • Multicellular organisms

  • Plants

  • Fish

  • Insects

  • Reptiles

  • Dinosaurs

  • Primates

  • First humans

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