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(5 B.Y.A.) Solar System Formation
The sun and other planets began forming by gravity and collisions of space debris. -
(4.6 B.Y.A.) Formation of the Earth
The earth formed by gravity pulling debris together. -
(4 B.Y.A.) Cooling of the Earth
The earth's surface began cooling and organic molecules began accumulating. -
(4 B.Y.A) Archaea-like Life
Archaea-like life existed on earth. -
(3.5 B.Y.A.) Stromatolites
Stromatolites are cyanobacteria that form large colonies and grow in layers. -
(3 B.Y.A.) Photosynthesis
Some forms of life had become photosynthetic. -
(2.2 B.Y.A.) Earth
The earth cooled and looks very similar to today. -
(2 B.Y.A.) Oxygen
Oxygen in the atmosphere reached today's levels. -
(1.5 B.Y.A) Endosymbiosis
Prokaryote began to live and reproduce. -
(1 B.Y.A.) Ozone
Ozone formed to protect organisms from harmful UV rays so they could exsist on land. -
(ca. 1625) First Microscope
It allowed scientists to closer examine living things. It led to the discovery of cells. -
(1668) Redi's Experiment
Redi placed rotting meat in a jar with and without a cover. Maggots formed in the jar without the lid and none with the lid. This proved that flies do not spontaneoulsy generate. -
(1768) Spallanzani''s Experiment
He boiled broth and sealed some of the flasks. The unsealed flask grew microorganisms. The sealed one did not grow microorganisms. This proved that microorganisms do not spontaneously generate. -
(1859) Pasteur's Experiment
He did the same experiment as Spallanzani, but used a curved necked flask showing that vital force could still be present, but not spotaneous generation. -
(1907) Radiometric Dating
Radiometric dating used half-lives of elements to determine how long a sample of something has meen decaying. It allows us to determine the earth's age. -
(1924) Oparin's Hypothesis
He thought early atmosphere contained ammonia. hydrogen gas. water vapor, and compounds of hydrogen and carbon. They recombined to be organic compounds. -
(1953) Urey and MIller
They tested Oparin's hypothesis with gases and electic sparks. He proved Oparin's hypothesis was correct. -
(1957) Sidney Fox
He did research on organisms that may have given rise to the first cells, such as coacervates and microspohere. It helped exlain where the first cells came from. -
(1967) Lynn Margulis
She proposted a theory of endosymbiosis; a small prokaryote is inside a larger one. The prokaryotes led to mitochondria. This helped discover why eukaryotic cells formed. -
(1982) Thomas Cech
He found type of RNA in some unicellular eukaryotes that could act as a catalyst. He led other scientists to discover that this RNA could self-replicate.
