1. Where did life on earth begin?
Origins of Life
Where did life on earth begin?

2. What is the difference between a law and a theory?
Law – a statement about the relationship between two or more things
Describes what is happening, rather than why or how
Laws describe what is happening, while theories seek to explain laws and why something is happening.
Theories do not become laws, theories explain laws.
Not all scientific laws have accompanying explanatory theories.
Teacher will explain that “law” and “theory” mean different things in different disciplines.
Theory – an explanation of why certain laws and facts exist
A well tested explanation

3. Primitive Earth (Early Earth)
So…
WHERE DID LIFE BEGIN?
HOW DID LIFE BEGIN?
In Margins of your notes…
Early Earth conditions:
Atmosphere contained CO2, water, methane, and ammonia
Lacked Oxygen (O2)
Without oxygen, life (as we know it today) could not be supported

4. Key Ideas in the Origin of Life
Spontaneous Generation (Abiogenesis): Living organisms develop from non-living matter
Biogenesis: Living things can only arise from other living things

5. Failed Attempts at Explaining the Origin of Life
Redi
Tested hypothesis of Spontaneous Generation (Abiogenesis)
Results: Disproved Spontaneous Generation
Pasteur
Actual success
Sided with: Biogenesis
Results: Life did not arise from non-life

6. EXPERIMENTS
Redi
Pasteur
What do you think this diagram is saying?

7. SUCCESS STORIES Miller-Urey Experiment
Simulated chemical conditions present on primitive earth
Made organic compounds from inorganic material
Compounds important to life could form on pre-biotic Earth

8. SUCCESS STORIES Endosymbiosis Endo- Inside Symbiotic- working Together
Mitochondria and Chloroplast were prokaryote cells that were eaten by a eukaryote cell
Prokaryotic cells gave rise to eukaryotic cells
EVIDENCE: Both mitochondria and chloroplast have their own DNA

9. Endosymbiotic Theory