SC.912.L.15.8

Conditions on early Earth

• The gases thought to be on early earth were ammonia, methane, carbon dioxide, and NO oxygen.

• The Miller-Urey experiment demonstrated that organic compounds could be made by passing a electric current (simulating lightning) through a closed system that held a mixture of gasses and water.

Theory of Endosymbiosis

• Explains the origin of chloroplasts and mitochondria and their double membranes.

• That chloroplasts and mitochondria are the result of years of evolution initiated by the endocytosis of bacteria and blue-green algae.

Eukaryotic Cells

• A cell with a nucleus • Present in all Eukaryotes (organisms whose

cells contain complex structures enclosed within membranes).

Chemical Evolution

• The formation of complex organic molecules from simpler inorganic molecules through chemical reactions in the oceans during the early history of the Earth

• The period of chemical evolution lasted less than a billion years.

Organic Molecules

• Organic molecules are molecules that are normally found in or produced by living systems.

• The are essential for life on Earth.

Louis Pasteur contributions

• Pasteur discovered the role of bacteria in fermentation.

• His experiments with bacteria conclusively disproved the theory of spontaneous generation and led to the theory that infection is caused by germs.

Contributions of Oparin

• In 1924 he put forward a theory of life on Earth developing through gradual chemical evolution of carbon-based molecules in primordial soup.

Contributions of Margulis

• Her most important work was the development of the serial endosymbiotic theory (SET) of the origin of cells, which posits that eukaryotic cells (cells with nuclei) evolved from the symbiotic merger of nonnucleated bacteria that had previously existed independently. In this theory, mitochondria and chloroplasts, two major organelles of eukaryotic cells, are descendants of once free-living bacterial species.

Miller and Urey

• The Miller-Urey experiment demonstrated that organic compounds could be made by passing a electric current (simulating lightning) through a closed system that held a mixture of gasses and water.