"The Origin of Life" (pgs 30-33)
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The Atmosphere of Early Earth
The First Cells
Life on Early Earth
Modeling Conditions on Early Earth
Support from Fossil Evidence
On ancient Earth, nitrogen, water vapor, carbon dioxide, and methane were probably the most abundant gases in the atmosphere.
They did not need water to survive
Earliest forms of life came between 3.5 and 4 billion years ago
Were unicellular organisms
the first life forms came from non-living materials
Two people make an experiment to test how organisms raised on earth
They placed water and a mixture of gasses to try to recreate Earths early atmosphere in a flask
Then they sent an electric current through the mixture to simulate lightning
After a week they found some chemical units that could be proteins, one of the building blocks of life
Unanswered Questions
Scientists have discovered fossils on archaea-like organisms that are 3.5 billion years old
This shows that cells may have existed back then
Those cells could not make there own food
Then later they could
They used to not need oxygen now they do
Many scientists today continue to explore the question of how life first arose on Earth
Scientist will continue to try to find out about the origin of life