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(5 BYA) Sun
Sun ignites, solar system takes shape -
(4.6 BYA) Earth
Molten Earth forms, lacks oxygen -
(4 BYA) Ocean
Ocean forms, organic molecules join the water and create amino acids. nitrogen bases, carbohydrates, and hydrocarbons -
(4 BYA) Moon, Crust
Moon forms by collision, Earth forms solid crust -
(3.5 BYA) Prokaryotes
Prokaryotes form, marine photosynthesis begins -
(3 BYA) Respiration
Respiration develops in mitochondria -
(2.2 BYA) Oxygen
Rapid rise in oxygen -
(2 BYA) Oxygen
O2 levels reached today’s levels -
(1.5 BYA) Eukaryotes
Eukaryotes form with a nucleus -
(1 BYA) Ozone Layer
Ozone (O3) formed – protected organisms from harmful UV rays so they could exist on land -
(1626) Francesco Redi
Francesco Redi’s experiment showed that flied are attracted to rotting meat, but don’t come from it. -
(1665, 1673) The First Microscopes
Hooke invents first microscope in 1665; Leeuwenhoek improves microscope in 1673 -
(1700's) Lazzaro Spalanzani
Lazzaro Spalanzani Showed that microorganisms don’t generate spontaneously either -
(1822) Louis Pasteur
Louis Pasteur used a curved-neck flask to show that even when the broth is exposed, microorganisms will not generate in the broth, but rather collect at the U-bend in the neck. -
(1924) Oparin's Hypothesis
Oparin’s hypothesized that early earth contained ammonia, hydrogen gas, water vapor, and methane. These high temperatures, along with lightning and UV radiation gave way to macromolecules such as proteins and eventually life forms. -
(1952) Miller-Urey Experiment
Miller-Urey experiment studied the possibility of life in early-earth conditions, testing Oparin's Hypothesis. -
(1960's) Lynn Margulis
Lynn Margulis proposeds that early prokaryotic cells developed an endosymbiotic relationship. -
(1960's) Sidney Fox
Sidney Fox did research on the physical structures that could have given way to the first life forms. -
(1970's) Thomas Cech
Thomas Cech studies transcription of a cell’s nucleus -
(1970's) Radiometric dating
Radiometric dating developed to find out how old organic specimens are.
