Transcript How did life on Earth begin?

How did life on Earth begin?
• Spontaneous generation-life from non life
• Search for truth
1. Redi 1668
2. Needham 1745
3. Spallanzani 1770
• Air contained “active
principle”
4. Pasteur 1864
- boil broth
- straight vs curved next open flasks
- support biogenesis- life from life
If life comes from life, then how
did life on Earth first arise?
• Earth 4.6 bya
• Big Bang
• Volcanism large role
in formation of
atmosphere and
oceans
• Methane, ammonia,
water, carbon
dioxide, nitrogen,
and hydrogen
Chemical Evolution
• Oparin Hypothesis 1924
- chemical reactions
between molecules w/o O2
• Miller and Urey 1953
- test Oparin’s hypothesis
- added electrical spark
- got “primordial soup”,
formation of organic
molecules amino acids,
sugars, and nucleotides
• Additional experiments
indicate RNA may be life’s
1st code
Miller’s
Experiment
Miller’s Products
Alternate Theories
• Meteorite 1969
• Deep Ocean Vents
What were the first cells like?
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Prokaryotic
Anaerobic
Heterotrophs
Over a period of time, cells became
autotrophic chemosynthesizers
• Set the stage for photosynthesis
• How was the atmosphere changed?
Unicellular to multicellular? How
did that happen?
• Formation of ozone layer
• Ability to perform aerobic
respiration
• Lynn Margulis
“endosymbioant theory”
- ancestors to today’s
eukaryotic cells preyed
upon other microbes
• Sexual reproductiongenetic variation new
species