Biology - Chp 17 - How Life May Have Begun On Earth - PowerPoint

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Biology - Chp 17 - How Life May Have Begun On Earth - PowerPoint

  1. 1. How Life May Have Begun on Earth
  2. 2. Cell Theory <ul><li>All living things are composed of cells </li></ul><ul><li>Cells are the basic unit of structure and function in living things </li></ul><ul><li>New cells are produced only from existing cells </li></ul>
  3. 3. Q: How were the first cells developed?
  4. 4. Heterotroph hypothesis <ul><li>An explanation for how early life forms may have developed on the primitive Earth </li></ul>
  5. 5. Assumptions <ul><li>Earth was hot </li></ul><ul><li>Lots of inorganic substances </li></ul><ul><ul><li>Hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen sulfide, water </li></ul></ul><ul><li>Lots of energy </li></ul>
  6. 7. <ul><li>Energy from the Earths environment helped create chemical bonds among particles in the seas </li></ul><ul><li>This made the first organic molecules like sugars, amino acids, and nucleotides </li></ul>
  7. 9. Testing the Heterotroph Hypothesis <ul><li>Stanley Miller & Harold Urey built the “Miller Urey apparatus” </li></ul><ul><li>This apparatus simulated the primitive environment </li></ul>
  8. 10. Miller Urey apparatus
  9. 11. More Testing of the Heterotroph Hypothesis <ul><li>Sidney Fox conducted further experiments that joined these organic compounds into aggregates, similar to “cell-like” structures </li></ul>
  10. 12. It is hypothesized that… <ul><li>Some of the large complex molecules formed aggregates which probably incorporated molecules from the seas as “food” </li></ul>
  11. 13. Q: What kind of nutrition is this? <ul><li>A: Heterotroph </li></ul><ul><li>In time, these aggregates became increasingly complex and organized </li></ul><ul><li>These aggregates are considered to be “alive” when they develop the ability to reproduce </li></ul>
  12. 14. How modern day Earth conditions were thought to be created <ul><li>It is thought that these heterotrophs evolved a pattern of respiration similar to the anerobic process of fermentation </li></ul>
  13. 15. Fermentation Pyruvic Acid + NADH alcohol + CO 2 NAD+
  14. 17. How modern day Earth conditions were thought to be created <ul><li>Some heterotrophs evolved a means of using carbon dioxide to synthesize organic compounds </li></ul>CO 2 + H 2 O + C 6 H 12 O 6 O 2 light (Carbon Dioxide) (Water) (Sun) (Glucose) (Oxygen)
  15. 18. Q: What kind of nutrition is this? <ul><li>A: Autotroph </li></ul>
  16. 19. With a Partner <ul><li>Do questions 5, 11, 21, 34, 35, 36 in your review books </li></ul>

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