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Aerobic Respiration

Do Now:. Aerobic Respiration. Early Human Technology. What earliest technology makes homo unique among animals?. Pan troglodyte. Homo neanderthalis. Ardipithicus (4.4 MYA). Not Tools… Chimpanzees use those too. FIRE!!!.

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Aerobic Respiration

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  1. Do Now: Aerobic Respiration

  2. Early Human Technology • What earliest technology makes homo unique among animals? Pan troglodyte Homo neanderthalis Ardipithicus(4.4 MYA)

  3. Not Tools… Chimpanzees use those too

  4. FIRE!!! • Archaeological sites in Asia and Europe indicate the first controlled use of fire occurred about 1,500,000 years ago. • The location of these ancient campfires coincides with the discovery of Homo erectus remains.

  5. The Importance of Fire • Chemically speaking, fire is a product of the oxidation of biomass. It is a very exothermic process. • CH2O + O2 CO2 + H2O • Fire releases the energy stored by plants during photosynthesis

  6. Fire & Cellular Respiration – Same Thing!!! • The examples shown have different amounts of energy stored in them. Rank them from least energy to greatest

  7. What Fire Represents • The discovery of fire represented an increase in the amount of energy available to humans. • We have used this energy to increase our numbers and colonize every continent! • Fire, and the combustion of fossil fuels, is nothing but an extension of our metabolic processes by other means.

  8. Burning = “Oxidation” • Oxidation state measures changes in the electronic structure of an atom • In general, a lower oxidation number represents a higher energy state. • Take carbon, for example: • CO2 = +4 ; C = 0 ; CH4 = -4

  9. Oxidation State of Carbon in: Lipids and Protein < -1 Carbohydrates 0 Hydrocarbons < -2 More Energy Less Oxidized Less Energy More Oxidized

  10. Oxidation and Reduction • Whenever something gets oxidized, the thing that oxidizes it gets reduced. • 2Fe +3O2 2Fe2O3 • Before the reaction, Fe = 0, O = 0 • After, Fe = +3, O = -2 • For every yin, there is a yang.

  11. What Does All This Mean??? • As usual, it’s all about the electrons.

  12. So… The bottom line • When a substance is oxidized, it: • Releases energy (exothermic) • Looses electrons • Increases oxidation state • Carbon is oxidized when burned, or used in cellular respiration. • Carbon is reduced during photosynthesis.

  13. Example: Burn Sugar and Follow the Carbon • C6H12O6 + 6O2 6CO2 + 6H2O • Before the exothermic reaction, the carbon in C6H12O6 has an oxidation number of 0. • During the reaction, carbon looses electrons. • After the reaction, the carbon (now in CO2) has an oxidation number of +4. • Carbon has been oxidized.

  14. Carbon Oxidation = Aerobic Life • The oxidation of carbon is the biochemical basis upon which almost all life rests. • The rate at which an individual or population can survive, grow, and reproduce is limited by how quickly it can get energy by oxidizing carbon.

  15. The Fire Outside… • Fire greatly increased homo’s access to energy. • With it, humans and their ancestors could: • Cook food, making new sources of nutrition available • Heat shelters, allowing them to live in colder climates • Carry a portable source of light.

  16. Growth requires Carbon

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