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HOW DID LIFE START?

HOW DID LIFE START? . Fransisco Redi (1668) Disproved “Spontaneous Generation Theory” People previously believed in abiogenesis : life comes from nonliving things . Fransisco Redi (1668). Showed this with an experiment using maggots and meat (meat without flies did not develop maggots) .

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HOW DID LIFE START?

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  1. HOW DID LIFE START? FransiscoRedi (1668) • Disproved “Spontaneous Generation Theory” • People previously believed in abiogenesis: life comes from nonliving things

  2. FransiscoRedi (1668) • Showed this with an experiment using maggots and meat (meat without flies did not develop maggots)

  3. Louis Pasteur (1859) • First stated the Law of Biogenesis (all life is from other life) • Conducted an experiment using S-shaped flasks and beef broth

  4. Louis Pasteur (1859) • The S - shape allowed air to enter the flask, but not contaminants • No microbes grew in the flask • When the flask was broken so contaminants could get in, microbes started to grow.

  5. Oparin and Haldane (1920) • Believed a combination of carbon dioxide, ammonia and ultraviolet radiation made organic compounds. • The early sea was “primordial soup” containing large populations of organic monomers and polymers.

  6. Oparin and Haldane (1920) • Haldane believed groups of monomers and polymers evolved lipid membranes, and that these developed into the first cell

  7. Miller and Urey (1950) • Tried to answer how organic molecules could have arisen in early earth • Simulated the conditions of early Earth in a laboratory setting (made primordial soup)

  8. Miller and Urey (1950) • Produced amino acids (organic molecule) by passing electricity through a mixture of hydrogen, methane, ammonia, and water. • Controversy over results • Scientists have been able to reproduce the experiments

  9. FROM PROKARYOTES TO EUKARYOTES (how the cells evolved) • The first cells were prokaryotic (no nucleus) and anaerobic (no oxygen) • By 2.2 bya photosynthetic bacteria (cyanobacteria) were releasing oxygen into the air

  10. FROM PROKARYOTES TO EUKARYOTES • The rise of oxygen in the air caused aerobic prokaryotes to evolve. • About 2 bya eukaryotic cells started to form

  11. The endosymbiotic theory says that eukaryotic cells evolved from prokaryotes that were living symbiotically (today those prokaryotic cells are seen as chloroplasts and mitochondria)

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