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Unit 11: Origin of Life and Evolution

Unit 11: Origin of Life and Evolution

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Unit 11: Origin of Life and Evolution

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  1. Unit 11: Origin of Life and Evolution

  2. THE ORIGIN OF EARTH • The Earth is approximately 4.6 billion years old

  3. Origin of Earth • The early Earth is different than Earth today • The sky was probably pinkish-orange rather than blue • The atmosphere contained hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen sulfide, and water vapor (this atmosphere would kill us!)

  4. No oxygen • No oceans because the Earth’s surface was too hot • HARSH conditions (volcanic activity, comets, and asteroids)

  5. Fantasia- Rite of Spring (Early Earth) • Around 3.8 billion years ago, the earth finally cooled off enough for water to condense into oceans.

  6. Fossils help us to figure out the Earth’s timeline. • We can tell how old fossils are by dating them. • There are two ways to date fossils.

  7. 1. Absolute Dating 2 types of geological dating How old fossils are in specific years Radioactive dating – uses radioactive isotopes that decay. The age is based on how much of the isotope (element) is left in the sample.

  8. Absolute – Radioactive Dating • Different isotopes are used based on the age of the sample. • Carbon 14 is used on organisms that are less than 60,000 years old. • Potassium 40 is used to date organisms that are billions of years old.

  9. 2 types of geological dating 2. Relative Dating • Comparing fossils by depth • The deeper the fossil is found, the older the fossil is. • The age of the fossil is relative to what is found below and above it. • May use distinct index fossils to compare ages • Example – magazine stacks

  10. So, again – how old is Earth? If all the time the Earth has been around was a latte . . . Hominids 3 million years0.06% Continental Drift 200 million years4% Abundant plant & animal remains 600 million years13% 4,600,000,000 YEAR OLD LATTE Solar System 4,600 million years

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

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

  13. 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

  14. 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.

  15. 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.

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

  17. 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)

  18. 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

  19. 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

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

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