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Cellular respiration

Cellular respiration is the process of extracting energy from glucose using oxygen in a series of reactions. The chemical equation for this aerobic process is C6H12O6 + O2 → 6CO2 + 6H2O + energy. During this process, glucose is oxidized to carbon dioxide while oxygen is reduced to water. Electrons move from less electronegative carbon to more electronegative oxygen, leading to a loss of potential energy and a decrease in free energy, resulting in an overall exergonic reaction. Enzymes play a crucial role by lowering the activation energy needed for these reactions.

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Cellular respiration

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  1. Cellular respiration Thursday, March 11

  2. The Big Picture • Cellular respiration • Harvesting energy from glucose using O2 • Use of O2 = aerobic • C6H12O6 + O2 6CO2 + 6H2O + energy • Accomplished via ~20 rxns (product of one is reactant for next, all catalyzed)

  3. The Big Picture • “Glucose is oxidized to carbon dioxide and oxygen is reduced to water.” • C6H12O6 + O2 6CO2 + 6H2O + energy • Hydrogen atoms carry electrons away from carbon atoms in glucose to oxygen atoms

  4. Redox Reactions • Loss of electrons = oxidation • Gain of electrons = reduction An electron transfer always involves an oxidation, reduction  “redox”

  5. How does this give us energy? LOGIC: • When the hydrogen atoms form covalent bonds with oxygen, the shared electron pairs are closer to the oxygen nucleus (oxygen is more electronegative than carbon is). • An electron occupying energy level closer to nucleus has less potential energy (similar to a skydiver closer to earth).

  6. How does this give us energy? LOGIC: 3. So, electrons that move from less electronegative carbon to more electronegative oxygen lose potential energy and achieve a LESS ordered state (not intuitive but whatever). 4. The decrease in potential energy coupled with an increase in entropy (electrons being closer to nucleus) causes a decrease in free energy and an overall exergonic reaction.

  7. How does this give us energy?

  8. 2nd part • C6H12O6 + O2 6CO2 + 6H2O + energy • Also an oxidation reaction

  9. 2nd part • C6H12O6 + O2 6CO2 + 6H2O + energy • Overall change = decrease in potential energy = increase in entropy • “Downhill process” • Energy= heat + light

  10. Why does this happen? • Glucose and O2 stable on their own • Presence of enzymes! • Lower EA • Obligate anaerobes • Obligate aerobes • Facultative anaerobes

  11. Cut and Paste Activity • C6H12O6 + O26CO2 + 6H2O + energy

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