Primordial Earth Theories on the Origin of Life. Early Earth and Evolution A THEORY of the origins...
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Transcript of Primordial Earth Theories on the Origin of Life. Early Earth and Evolution A THEORY of the origins...
Early Earth and EvolutionEarly Earth and EvolutionA THEORY of the origins of the universe A THEORY of the origins of the universe
Big BangWhen?
-Approx. 13.5 Billion years ago expansion from singularity-MASSIVE AMOUNTS OF ENERGY!-Energy eventually converted to fundamental building blocks of matter.
Evidence?-Expanding universe-Background radiation-Abundance of Hydrogen
After Big Bang…….After Big Bang…….• Stars!
– Need hydrogen gas fusion– Form heavier elements– Really big stars go out with a bang supernova!
• Planets!– Leftover “mess” from supernova start to accrete
into larger objects. (NEWTONS LAW!)– Typically these objects will orbit around a star
• SOLAR SYSTEMS!
LIFE!!!!LIFE!!!!
• Spontaneous Generation.– Theory (hypothesis actually) that life can
randomly emerge from non-living thing
• Biogenesis – Theory that life only comes from pre-existing life.
• Common Ancestor– Theory that every living organism on the planet
is a descendent of an original cell
• Question : Where did first life come from???
Oparin-Haldane HypothesisOparin-Haldane Hypothesis
• All the elements were already present on Earth.
• Early atmosphere contained mostly ammonia NH3, hydrogen gas H2, water H2O, and methane CH4.
• High temperatures might cause gases to form simple organic compounds.
““Prebiotic Soup”Prebiotic Soup”
• As Earth cooled simple organic compounds collected in the lakes and seas.
• Energy from lightning and UV radiation caused chemical reactions to build macromolecules.
Key ExperimentsKey Experiments• Francisco Redi’s Flies –
–Where do maggots come from
–Bottom Line: no spontaneous generation
Key ExperimentsKey Experiments• Spallanzani –
–Bacteria in broth come from air? Or other microbes?
–Bottom Line: no spontaneous generation
Key ExperimentsKey Experiments• Louis Pasteur –
–Bacteria in broth come from air? Or other microbes?
–Key difference from spallanzani?–Bottom Line: no spontaneous generation
1953: Miller- Urey1953: Miller- Urey
• Stanley Miller and Harold Urey set up an apparatus to simulate the proposed primordial Earth conditions.
1953: Miller- Urey1953: Miller- Urey
• Stanley Miller and Harold Urey set up an apparatus to simulate the proposed primordial Earth conditions.
• Found organic compounds.
Debatable points:Debatable points:• Atmosphere probably contained CO,
CO2, and N2
• Presence of O2, and CO2 interfere with production of organic compounds.–Organic compounds produced in
undersea volcanoes.• Organic compounds came from outer
space.
Pre-Cell StructuresPre-Cell Structures
• Organic molecules aggregate spontaneously.
• Microsphere: Protein membrane structure
• Coacervates: Droplets of lipids amino acids, and sugars.
First Cells: ProkaryoticFirst Cells: Prokaryotic• Environment: Little or no oxygen
Cells were anaerobic.• Environment: Organic food
molecules
Cells were heterotrophs.• Oldest fossils look like prokaryotes.
Cells were prokaryotes.
ArchaeaArchaea
• Present day cells, thought to be similar to earliest cells.
• Unicellular organisms that thrive in harsh environmental conditions.–Anaerobic metabolism.–Inorganic energy sources.
Endosymbiotic TheoryEndosymbiotic Theory
Creating the first eukaryotes:
• Large prokaryotes engulfed smaller prokaryotes.
• Mutually beneficial relationship: small cells are protected and large cell gets energy.
• Small aerobic cells evolved into
• Small photosynthetic cells evolve into
• Mitochondria and chloroplast have their own DNA.
• DNA is circular, like prokaryotes.
• Replicate independently of cell.• http://www.youtube.com/watch?v=dSjg_uYS_QY&feature=related
chloroplast.
mitochondria