1. The Evolutionist Theory of the Origin of Life
Packet #62
Chapter #26
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2. Geologists & The Early Earth
Already discussed are macro and micro-evolution, but how do scientists hypothesize the origin of life?
Biologists generally agree that life originated from non-living matter.
Chemical Evolution
The spontaneous production, and accumulation, of small organic molecules from inorganic molecules.
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3. Chemical Evolution Is very difficult to test experimentally
Four Requirements
Little or no free oxygen
A source of energy
The availability of chemical building blocks
Water
Minerals
Gases present in the atmosphere (All necessary to form organic molecules)
Time
Necessary for molecules to accumulate and react.
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4. Formation of Organic Molecules
There are two hypotheses proposed
Prebiotic Soup Hypothesis
Organic molecules formed near Earth’s surface in a “sea of organic soup” or on rock or clay surfaces.
Iron-sulfur World Hypothesis
Suggests that organic molecules were produced at hydrothermal vents
Cracks in the deep ocean floor
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5. RNA World Model
FORMATION OF CELL
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6. Formation of Cells RNA World Model
After small organic molecules were formed, macromolecules were assembled from them.
Protobionts were formed from macromolecules
Macromolecular assemblages
Cells then arose from the macromolecular assemblages
The first cell is thought to be a prokaryote bacteriophage
Anaerobe
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7. RNA—The Organic Molecule
RNA, a type of nucleic acid, is a type of organic macromolecule.
RNA World Model
RNA was the first informational molecule to “evolve” in the progression towards a self-sustaining and self-supporting cell
Natural selection at the molecular level resulted in the information sequence
DNA-->RNA-->protein
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8. Endosymbiont Theory
FORMATION OF CELLS
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9. Endosymbiont Theory Endosymbiont Theory
Eukaryotic cells arose from prokaryotic cells.
Certain organelles found within eukaryotic cells evolved from prokaryotic endosymbionts with larger prokaryotic hosts.
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10. IMPACT OF CELLS
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11. How Prokaryote Hetereotrophs Impacted the Environment
Autotrophs, organisms that produce their own food, arose from the prokaryotic hetereotrophs
The evolution of photosynthesis changed early life because oxygen was generated
Oxygen accumulation in the atmosphere allowed the evolution of aerobes
Organisms that use oxygen for a more efficient cellular respiration.
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12. The Geologic Record Table 26.1 Page 519
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13. Figure 26.20
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