Cellular Respiration: Harvesting Chemical Energy

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Cellular Respiration Harvesting Chemical Energy
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Respiration is the process of extracting stored
energy from glucose to make ATP.
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Cellular Respiration Equation

• C6H12O6 6 O2 6 CO2 6 H2O and energy
• As a result of respiration, energy is released
  from the chemical bonds found in complex organic
  molecules (food).

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Aerobic Respiration

• Aerobic Respiration is respiration which takes
  place in the presence of oxygen

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Respiration is controlled by Enzymes
rate is controlled by enzymes
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Cell Respiration is divided into 3 stages.
(components)

• 1. Glycolysis
• 2. Krebs Cycle
• 3. Oxidative Phosphorylation

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Glycolysis

• Glyco- glucose, -lysis to split
• Universal step in all forms of respiration
• Likely used to supply energy for the ancient
  cells.

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Glycolysis

• Function - To split glucose and produce NADH, ATP
  and Pyruvate (pyruvic acid).
• Location - Cytoplasm.
• Occurs in 9 steps. 6 of the steps use magnesium
  Mg as cofactors.

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NAD Energy carrier

• Nicotinamide Adenine Dinucleotide
• NAD 2 e- NADH
• NAD oxidized form
• NADH reduced form

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Requirements for Glycolysis

• Glucose
• 2 ATP. As activation energy
• 4 ADP
• 2 NAD
• Enzymes

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The Products of Glycolysis

• 2 Pyruvic Acids (a 3C acid)
• 4 ATP
• 2 NADH

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Net Energy Result

• 2 ATP per glucose
• 2 NADH
• In summary, glycolysis takes one glucose and
  turns it into 2 pyruvate, 2 NADH and a net of 2
  ATP.

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Krebs CycleAlso called Citric Acid Cycleor
Tricarboxylic Acid Cycle

• Function Oxidize pyruvic acid to CO2
• Produce 3NADH, 1FADH2 and 1ATP
• Location Mitochondria matrix

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Formation of Acetyl CoAAcetyl CoA is formed
when the pyruvate , from glycolysis, combines
with Coenzyme A tis takes place in the matrix.
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Requirements for Krebs Cycle

• Pyruvic acid (3C acid)
• Coenzyme A
• 3 NAD
• 1 ADP
• 1 FAD
• Double this list for each glucose.

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Products of Krebs Cycle

• 3 CO2
• Acetyl CoA
• 3 NADH
• 1 ATP
• 1 FADH2
• Double this list for each glucose.

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Krebs Cycle

• Produces most of the cell's energy in the form of
  NADH and FADH2 not ATP
• Does NOT require O2
• The CO2 produced by the Krebs cycle is the CO2
  animal exhale when they breathe.

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Oxidative Phosphorylation

• Process of extracting to energy from NADH and
  FADH2 to form ATP.
• Function Convert NADH and FADH2 into ATP.
• Location Mitochondria cristae.

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Oxidative Phosphorylation

• NADH or FADH2
• ADP
• O2

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Oxidative Phosphorylation

• Requires the Electron Transport Chain the
  Electron Transport Chain is a collection of
  proteins, embedded in the inner membrane, used to
  transport the electrons from NADH and FADH2

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Cytochrome c

• Cytochrome c is one of the proteins of the
  electron transport chain often used by
  geneticists to determine relatedness exists in
  all living organisms.
• The Cytochromes alternate between RED and OX
  forms and pass electrons down to O2

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ATP Yield

• Each NADH energizes 3 ATP
• Each FADH2 energizes 2 ATP

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Chemiosmotic Hypothesis

• ETC energy is used to move H (protons) across
  the cristae membrane.
• ATP is generated as the H diffuse back into the
  matrix through ATP Synthase

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ATP Synthase

• Uses the flow of H to make ATP.
• Works like an ion pump in reverse, or like a
  waterwheel under the flow of H water.

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Alcoholic Fermentation

• Carried out by yeast, a kind of fungus.

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Alcoholic Fermentation

• Uses only Glycolysis.
• An incomplete oxidation - energy is still left in
  the products (alcohol).
• Does NOT require O2
• Produces ATP when O2 is not available.

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Lactic Acid Fermentation

• Uses only Glycolysis.
• An incomplete oxidation - energy is still left in
  the products (lactic acid).
• Does NOT require O2
• Produces ATP when O2 is not available.

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Lactic Acid Fermentation

• Done by human muscle cells under oxygen debt.
• Lactic Acid is a toxin and causes soreness and
  stiffness in muscles.

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Fermentation - Summary

• Way of using up NADH so Glycolysis can still run.
• Provides ATP to a cell even when O2 is absent.

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Aerobic vs Anaerobic

• Aerobic - Respiration with O2
• Anaerobic - Respiration without O2
• Aerobic - All three Respiration steps.
• Anaerobic - Glycolysis only.

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Strict vs. Facultative Respiration

• Strict - can only carry out Respiration one way
  aerobic or anaerobic.
• Facultative - can switch respiration types
  depending on O2 availability. Ex - yeast

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ATP yields by Respiration type

• Anaerobic - Glycolysis only Gets 2 ATPs per
  glucose.
• Aerobic - Glycolysis, Krebs, and Oxidative
  Phosphorylation (electron transport chain)
  Generates many more ATPs per glucose.

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Aerobic ATP yield

• Glycolysis - 2 ATPS, 2 NADHs
• Krebs - 2 ATPS, 8 NADHs, 2 FADH2
• Each NADH 3 ATP
• Each FADH2 2 ATP

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ATP Sum

• 10 NADH x 3 30 ATPs
• 2 FADH2 x 2 4 ATPs
• 2 ATPs (Gly) 2 ATPs
• 2 ATPs (Krebs) 2 ATPs
• Max 38 ATPs per glucose

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However...

• Some energy is used in shuttling the NADH from
  Glycolysis into the mitochondria.
• Actual ATP yield 36/glucose

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Yeast

• Would rather do aerobic Respiration it has 18x
  more energy per glucose.
• But, anaerobic will keep you alive if oxygen is
  not present.

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Importance of fermentation

• Alcohol Industry - almost every society has a
  fermented beverage.
• Baking Industry - many breads use yeast to
  provide bubbles to raise the dough.

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Summary

• Know the 3 main reactions of Respiration and the
  4 required items for each.