AP Bio Ch 9, part 1


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AP Bio Ch 9, part 1

  1. 1. An Overview of Cellular Respiration Chapter 9 g ’s gettin He l chemica m f ro energy is food! h
  2. 2. DO NOW • 1. 2. 3. Take out a piece of binder paper & fold it into thirds Top third – furthest place you’ve ever traveled Middle third – name of your first pet Bottom third – last person you hugged Ankara, Turkey Tiger Mitch
  3. 3. The Big Picture • All cells require energy to do their work • Cellular respiration produces this energy
  4. 4. What is cellular respiration? • It is the main way that chemical energy is harvested from food • Food molecules have LOTS of energy – but that energy can’t be used all at once • Food energy is stored as ATP energy Breathing Muscle cells Cellular respiration
  5. 5. Cellular respiration releases energy • Cellular respiration is catabolic and exergonic C6H12O6 + 6O2 --> 6CO2 + 6H2O + Energy (ATP and heat) ∆G = -686 kcal/mol of glucose broken down
  6. 6. • Catabolic reactions are not directly used to power the cell • The energy released is stored in molecules of ATP • ATP is then used to power the cell
  7. 7. Quick Think 1 – hug buddies • Why don’t organisms use the metabolic breakdown of food directly to power the cell? • In other words, why bother making ATP?
  8. 8. General Information about redox reactions • Redox = oxidationreduction reactions • Cellular respiration is a series of redox reactions
  9. 9. Many chemical reactions involve the transfer of electrons from one molecule to another • These kinds of reactions • The loss of are called redox electrons from a reactions substance = oxidation • The addition of electrons to a substance = reduction
  10. 10. • The electron donor = reducing agent (it reduced the other substance) • The electron acceptor = oxidizing agent
  11. 11. Quick Think 2 – travel buddy • In the following redox reaction, which compound is oxidized and which is reduced? C4H6O5 + NAD+  C4H4O5 + NADH + H+
  12. 12. Oxygen is a powerful oxidizing agent • Oxygen is very electronegative • The more electronegative an atom is, the more energy it takes to pull away its electrons
  13. 13. When electrons move from a less electronegative atom to a more electronegative atom, it releases energy • A reaction that puts electrons closer to oxygen releases energy
  14. 14. Respiration - the oxidation of glucose by oxygen • During cellular respiration, hydrogen and its bonding electrons change partners • Hydrogen and its electrons go from sugar to oxygen, forming water Oxidation [Glucose loses electrons (and hydrogens)] [Oxygen gains electrons (and hydrogens)] Reduction
  15. 15. The Overall Equation for Cellular Respiration Oxidation: Glucose loses electrons (and hydrogens) Glucose Carbon dioxide Electrons (and hydrogens) Oxygen Reduction: Oxygen gains electrons (and hydrogens) Energy
  16. 16. • Why does transferring electrons to oxygen release energy? When electrons move from glucose to oxygen, it is as though they were falling This “fall” of electrons releases energy during cellular respiration Release of heat energy
  17. 17. Glucose is a good fuel • It has a lot of hydrogens • Makes it a reservoir of electrons • Those electrons want to go to a lower energy state by moving toward the more electronegative oxygen
  18. 18. Quick Think 3 – pet buddy • Redox reactions involve ___________. • Oxygen is very __________ so it is a good _________. • In cellular respiration, oxygen is used to _________ glucose, thereby releasing __________ due to the fall of ___________ from glucose to ____.
  19. 19. • Enzymes help glucose get oxidized in a series of controlled steps • So that the energy being released is released in a controlled, useful way
  20. 20. Overall redox summary of cellular respiration • Cellular respiration = electrons in glucose --> NADH --> electron transport chain --> oxygen