Biology Timeline
Essay by 24 • November 6, 2010 • 399 Words (2 Pages) • 1,548 Views
4.5 Billion years ago
* Gas condenses: Gravity compresses the hot particles thus forming our planet.
* Our planet cools: heat and gas escape the crust through volcano's.
4.0 Billion years ago
* Rain and steam create oceans: Evaporation produces a rich soupy breeding ground
* Hydrogen, nitrogen, CO2 and other elements hang in the air and dissolve in the water where much of the action takes place.
* DNA forms and self replicates - one chain can copy the other.
3.5 Billion years ago
* Cell walls surround the replicating
3.0 Billion years ago
* Because DNA continues to replicate within the cell wall... A single compartment divides into 2 cell division.
* Some microorganisms "learn" to convert sunlight into sugar. (Photosynthesis)
* (Remember...we are still under water)
* A few microorganisms "learn" to use the waste O2 of photosynthesis...
* Cells develop modes of locomotion
3.0 - 5.0 Million years ago
* The waste of photosynthesis is oxygen. O2 escapes the ocean and begins to accumulate in the atmosphere, eventually forming the ozone. Ozone protects from solar radiation. Making the land/air habitable.
1.5 Billion years ago
* Cells begin
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