Early Earth • About 4.6 billion years old • Life about 3.8 Bya • Hot, gaseous, no oxygen, no ozone, volcanic hot mess…… • Simple life forms around 3.4 billion years • Hydrogen (H2), methane (CH4), ammonia (NH3), and water vapor (H2Og)
Miller and Urey, 1953 • Recreated what scientists theorize was atmospheric conditions of early Earth and used electricity to simulate lightning • Theorized that organic compounds (and yes, we’re organic) came from inorganic compounds • Organic refers to carbon compounds (aside from carbon monoxide and carbon dioxide) • This is important because life-forms as we know it are all carbon-based
Miller and Urey Entry for hydrogen, methane, water vapor, and ammonia gases Electrode High voltage source Condenser for cooling Boiling water Solution of organic compounds
Miller and Urey’s Results • 10-15% of the carbon was in the form of organic compounds. • 2% of the carbon had formed some of the amino acids which are used to make proteins • showed that organic compounds such as amino acids, which are essential to cellular life, could be made easily under the conditions that scientists believed to be present on the early earth.
Juan Orno - 1961 • found that amino acids could be made from hydrogen cyanide (HCN) and ammonia in an aqueous solution (water solution) • also found that his experiment produced an amazing amount of the nucleotide base, adenine • A component of DNA, RNA and ATP
Hmmmmm…are we aliens?? (Just some interesting info…..) • Many of the compounds made in the Miller/Urey experiment are known to exist in outer space. • September 28, 1969, a meteorite fell over Murchison, Australia. Analysis of the meteorite has shown that it is rich with amino acids. • Over 90 amino acids have been identified by researchers to date. Nineteen of these amino acids are found on Earth. • The early Earth is believed to be similar to many of the asteroids and comets still roaming the galaxy. • If amino acids are able to survive in outer space under extreme conditions, then this might suggest that amino acids were present when the Earth was formed. • More importantly, the Murchison meteorite has demonstrated that the Earth may have acquired some of its amino acids and other organic compounds by planetary in fall.
First “Cells” ? • Thought to have arisen by the enclosure of self-replicating RNA and enclosed by a phospholipidbilayer (a “protocell”)
FIRST BACTERIA? • Found in northwest Australia's Pilbara region • Microscopic fossils show convincing evidence for cells, and bacteria, living in an oxygen-free world over 3.4 billion years ago. • The ancient microbes likely fed on sulfur, as many bacterial organisms do today.
Cell Evolution 2 bya First unicellular eukaryotes appear (microscopic and have a nucleus!!) 1.2 bya Multicellular eukaryotes (Grypaniaspiralis) 3 bya Photosynthetic Prokaryotes appear….. (cyanobacteria/aka blue- green algae but are bacteria…NOT algae; contained chlorophyll And produced O2) 3.5 bya Anaerobic Prokaryotes appear (did not need O2)