Transcript Origin of Life - Solon City Schools

Origin of Life
Early Earth Landscape
Early Earth Landscape
History of the Earth
In a single day.
Courtesy: NASA / Goddard Space Flight Center
12.00 to 4.00am



“The Big
Bang”
No life
A planet with
poisonous
gases in the
air, no soil and
a hot sea.
4.00am to 8.00pm

Single celled organisms, called
stromatolites, begin to produce oxygen.
Just before 8.30pm

First marine plants
8.50pm
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Jellyfish and
simple marine
organisms
Just after 9.00pm
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Trilobites and creatures of the Burgess
Shale
10.00pm

Plant life of the
carboniferous
and the first
land creatures.
11.00pm to 11.45pm

Reign of the Reptiles – Dinosaurs Rule!
1 minute and 17
seconds to midnight

First humans appear.
Clock
analogy for
some key
events in
evolutionary
history
What was early Earth like?

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Very hot!
The friction of colliding
meteorites could have
heated its surface
The compression of
minerals and the decay
of radioactive materials
heated its interior
Atmosphere?

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Volcanoes might have spewed lava and
gases, relieving some pressure in Earth’s
interior
These gases helped form Earth’s ancient
atmosphere
–
Little free oxygen
– A lot of water vapor and other gases
• Carbon dioxide, nitrogen, hydrogen, methane,
ammonia
How did life originate?

Spontaneous Generation
–
Idea that nonliving material can produce life
– Can you give me an example of what Aristotle
was seeing?
Spontaneous Generation

Francesco Redi was the first to disprove this
idea.
–
How do you think he did it?
Spontaneous Generation

Louis Pasteur went on to disprove it as well.
Meteorites

What might have been carried on the
meteorite?
Soups On!
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Earth’s atmosphere was probably made up
of gases that contained organic elements.
What are they??
Primordial Soup

Energy fueled chemical reactions among
these gases which combined them into
organic compounds.
Primordial Soup

These molecules were washed into the
oceans, mixing together
Theories on how life began

Alexander Oparin
–
Life began in the oceans
– Energy from the sun, lightning, and Earth’s
heat triggered chemical reactions to produce
small organic molecules
Chemical Evolution
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Harold Urey and Stanley Miller provided
evidence to support this.
Chemical Evolution
Miller Urey Results
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After a week, they found several kinds of
amino acids, sugars, and other small organic
molecules
Evidence supported Oparin’s hypothesis!
Life began in the oceans and Energy from
the sun, lightning, and Earth’s heat
triggered chemical reactions to produce
small organic molecules
1. The earth was formed ~4.5 billion years ago
2. It took ~500 million years for the crust to solidify.
3. 3.9 bya Earth might have cooled enough for water in its
atmosphere to condense; led to millions of years of
rainstorms with lightning – ENOUGH TO FILL EARTH’S
OCEANS!
4. The oldest fossils of microorganisms (earliest evidence of
life)
• 3.5 billion years old,
• embedded in rocks in western Australia
Prokaryotes dominated from 3.5 to 2 billion years ago.
- During this time, the first divergence occurred:
Bacteria and Archaebacteria
Oxygen began accumulating in the atmosphere
about 2.7 billion years ago.
a. Cyanobacteria are photosynthetic
prokaryotes that are still present today 
produced oxygen.
Banded iron formations are evidence of the age of
oxygenic photosynthesis – approximately 2 BYA in
photo
5. The oldest eukaryotic fossils are ~2 billion
years old.
a. Symbiotic community of prokaryotes
living within larger prokaryotes.
 Mitochondria and chloroplasts
6. The oldest fossils of multicellular organisms
are ~1.2 billion years old.
7. Fossilized animal embryos from Chinese
sediments 570 million years ago.
8. Plants, fungi, and animals began colonizing
land ~500 million years ago.
a. First plants transformed the landscape…
b. Then animals were able to take advantage
of new niches
 Mammals evolved 50 to 60 million years
ago.
Some
major
episodes in
the history
of life.