Chapter 9: Cellular Respiration

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Chapter 9 Cellular Respiration

• 9.1 Chemical Pathways
• 9.2 The Krebs Cycle and Electron Transport

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Ch. 9 Map
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Cellular Respiration
Calorie
Aerobic
3 Stages
Glycolysis
Equation
Citric Acid Cycle
Electron Transport Chain
Krebs Cycle
Anaerobic
Pyruvic Acid
Fermentation
Alcoholic Fermentation
Lactic Acid Fermentation
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Getting Energy to Make ATP

• A Review
• The mitochondria in cells breaks down glucose and
  produces energy-in this case ATP.
• Cellular Respiration breaking down glucose to
  make ATP

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Cellular Respiration

• Three stages of cellular respiration
• Glycolysis - anaerobic
• The Citric Acid Cycle (Krebs Cycle) - aerobic
• The electron transport chain aerobic
• The aerobic phase produces the most ATP
• ? ? ? The process begins with food molecules
  (glucose) that are broken down into usable energy
  (ATP).

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Overview of Cellular Respiration
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Glycolysis

• Takes place in the cytoplasm of the cell
• It requires no oxygen (anaerobic).
• Glucose (a 6 carbon molecule) is broken down into
  2 molecules of pyruvate (a 3 carbon compound).
• It requires 2 ATP
• It produces 4 ATP
• A net gain of 2 ATP

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Glycolysis
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The Citric Acid Cycle

• Takes place in the mitochondria of the cell.
• Review Inner folded membranes.
• The pyruvate from glycolysis is slightly modified
  before the citric acid cycle begins.
• These new molecules (called Acetyl Coenzyme A)
  are broken down to form ATP and CO2.
• One ATP per cycle is produced, two cycles occur
  per glucose molecule.
• Generates high energy electrons carried by NADH
  and FADH2

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Citric Acid Cycle/Krebs Cycle
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The Electron Transport Chain

• The final stage of respiration
• Similar to the events of the protein chain in
  photosynthesis.
• Electrons are passed from protein to protein, and
  the energy they give off is used to produce more
  ATPs.
• ? ? ? The final electron acceptor is an oxygen
  atom.
• This is why we cannot live without oxygen!
• Collects H ions and low energy electrons!
  (waste)
• pg. 228 Fig. 9.7

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Electron Transport Chain
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Where do the electrons come from?

• Electrons for the ETC come from electron
  carriers FADH2 and NADH
• Work like NADPH (from photosynthesis)
• Formation of FADH2 and NADH occurs during
  glycolysis and citric acid cycle
• Glycolysis
• NAD and H combine with e- to make NADH
• Citric Acid Cycle
• More NADH forms
• FAD and H combine with e- to make FADH2

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Respiration

• One glucose molecule is capable of producing a
  net amount of 34-38 ATP
• 2 in glycolysis
• 2 from the Citric Acid Cycle
• Up to 34 from the electron transport chain

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Fermentation

• When oxygen isnt available, the aerobic stages
  of respiration obviously cant begin.
• In this situation, fermentation begins after
  glycolysis as an alternate form of respiration.
• Why can glycolysis still go on?
• Fermentation provides small amounts of ATP until
  the cell can once again obtain enough oxygen to
  begin the aerobic stages of respiration. does
  not last long

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Fermentation

• Two main types p. 225, Fig. 9.4
• Alcoholic Fermentation
• Common in yeast cells. CO2 and alcohol is
  produced.
• Example bread
• Lactic Acid Fermentation
• Occurs in animal muscle cells. Lactic acid is
  produced.
• Example pain in muscles from exercise

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Yeast in Bread

• Yeast is a fungus
• It consumes the
• Sugar in the dough
• -Dough is left to rise
• -Yeast produces alcohol and CO2 during
  fermentation
• -Alcohol evaporates as bread cooks
• -CO2 makes bubbles holes in bread

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ATP and Exercise

• Running
• Sprinting uses energy
• Stored in muslces runs out quickly within
  seconds
• Made by lactic acid fermentation (oxygen
  depleted)
• made quickly, runs out quickly (about 90
  seconds) lactic acid produced burning
  sensation in legs
• Explains why a sprinter breathes very heavily at
  the end of a race
• Long Term Energy
• Made by cellular respiration needs oxygen which
  is why runners breathe heavily
• Makes energy slower than fermentation runners
  pace themselves
• Glycogen stores last for about 15-20 minutes of
  activity
• After that, body breaks down fats and other
  stored molecules for energy
• Aerobic Exercises help with weight control

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Important Study Tips

• Table 9.10 on p. 232.
• Aerobic/Anaerobic
• Photosynthesis/Respiration/Fermentation
• Alcoholic/Lactic Acid Fermentation
• Citric Acid Cycle/Calvin Cycle
• Light Dependent/Light Independent Rxns.
• ATP/ADP
• Strohelloma/Stoma/Stomata
• Xylem/Phloem
• What is the definition of a cycle?