• Overview: Life Is Work• Overview: Life Is Work
• Living cells
– Require transfusions of energy from outside
sources to p...
• The giant panda• The giant panda
– Obtains energy for its cells by eating plants
Copyright © 2005 Pearson Education, Inc...
• Energy• Energy
– Flows into an ecosystem as sunlight and
leaves as heat Light energy
ECOSYSTEMECOSYSTEM
CO + H O
Photosy...
Capacity to do work
Kinetic energy
› energy of motion
› moving objects perform work by imparting motion to› moving objects...
Totality of an organism’s chemical process
CATABOLIC PATHWAYSCATABOLIC PATHWAYS
Release energy by breaking down complex
mo...
ExergonicExergonic
› Proceeds with a net release of energy
› occurs spontaneously
› “Downhill”
Endergonic
› Absorbs free e...
Transfer of electrons from a LESS
electronegative substance to a MORE
l i b ?electronegative substance?
Downhill reaction ...
Adenosine Triphosphate
Immediate source of energy that powers
cellular work
Phosphates bonds
are so fragile
V t bl- Very unstable
When ATP is hydrolyzed, it releases free
energyenergy
Th ll l th tThe cell couples the energy to
endergonicendergonic proc...
-Aerobic respiration
-FermentationFermentation
“The wholesale release of energy from fuel
is difficult to harness efficiently for
i k”constructive work”
Cellular respira...
Three metabolic stages
1. Glycolysisy y
› Cytosol
› Breakdown of glucose into 2 molecules of pyruvate
2. Krebs cycle
› Mit...
Substrate
phosphorylationphosphorylation
› When any enzyme
transfers a
phosphate group
from a substrate to
ADPADP
Oxidative phosphorylation
› Electrons are passed from one electron acceptor› Electrons are passed from one electron accept...
1. Energy investment Phasegy
2. Energy payoff phase
Glucose enters the cell
DEBIT: 2 ATP molecules
Ready for splitting
Downhill reaction
S b t t h h l ti
Water extraction forms double bond
Substrate phosphorylation
Aka Citric Acid Cycley
•Occurs in the inner
membrane of mitochondria
Inc electronegativityInc electronegativity
Final electron
acceptoracceptor
ETC makes no ATP directly
How does the mitochondrion couple ETC
and energy release to ATP synthesis?gy y
CHEMIOSMOSIS
H+ gradient couples the redox reactions
of ETC to ATP synthesis
PROTON MOTIVE FORCE
NADH- 3 pumps= 3 ATPsNADH 3 pumps= 3 ATPs
FADH2 – 2 pumps= 2 ATPs
Fermentation enables some cells toFermentation enables some cells to
produce ATP without the use of oxygen
Cellular respir...
GlycolysisGlycolysis
› Can produce ATP with or without oxygen, in
aerobic or anaerobic conditionsaerobic or anaerobic cond...
Fermentation consists ofFermentation consists of
› Glycolysis plus reactions that regenerate NAD+,
which can be reused by ...
In alcohol fermentation
› Pyruvate is converted to ethanol in two steps,
one of which releases CO2
D i l ti id f t tiDuring lactic acid fermentation
› Pyruvate is reduced directly to NADH to form
lactate as a waste produc...
Both fermentation and cellular respiration
› Use glycolysis to oxidize glucose and other
organic fuels to pyruvate
Fermentation and cellular respiration
› Differ in their final electron acceptor
Cellular respiration
› Produces more ATP
• Pyruvate is a key juncture in catabolism• Pyruvate is a key juncture in catabolism
Glucose
CYTOSOL
Pyruvate
No O2 presen...
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Comparison of ETC in Photosynthesis and
RespirationRespiration
Mitochondria ChloroplastMitochondria
Electrons from food
molecules (oxidation
Chloroplast
Do not need food to
make ATPmole...
Respiration
Respiration
Respiration
Respiration
Respiration
Respiration
Respiration
Respiration
Respiration
Respiration
Respiration
Respiration
Respiration
Respiration
Respiration
Respiration
Respiration
Respiration
Respiration
Respiration
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Respiration

  1. 1. • Overview: Life Is Work• Overview: Life Is Work • Living cells – Require transfusions of energy from outside sources to perform their many taskssources to perform their many tasks Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  2. 2. • The giant panda• The giant panda – Obtains energy for its cells by eating plants Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 9.1
  3. 3. • Energy• Energy – Flows into an ecosystem as sunlight and leaves as heat Light energy ECOSYSTEMECOSYSTEM CO + H O Photosynthesis in chloroplasts C ll l Organic + OCO2 + H2O Cellular respiration in mitochondria molecules + O2 ATP powers most cellular work Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Heat energyFigure 9.2
  4. 4. Capacity to do work Kinetic energy › energy of motion › moving objects perform work by imparting motion to› moving objects perform work by imparting motion to other matter › Water gushing through dam turn turbines › Light to power photosynthesis› Light to power photosynthesis Potential energy St d› Stored energy › Based on location or structure › Energy stored in molecules
  5. 5. Totality of an organism’s chemical process CATABOLIC PATHWAYSCATABOLIC PATHWAYS Release energy by breaking down complex molecules to simpler compoundsmolecules to simpler compounds Cellular respiration ANABOLIC PATHWAYS Consume energy to build complicated molecules f i lfrom simpler ones Protein synthesis from amino acids
  6. 6. ExergonicExergonic › Proceeds with a net release of energy › occurs spontaneously › “Downhill” Endergonic › Absorbs free energy from its surrounding St f› Stores free energy › Non spontaneous › “Uphill”› Uphill
  7. 7. Transfer of electrons from a LESS electronegative substance to a MORE l i b ?electronegative substance? Downhill reaction or Uphill reaction?
  8. 8. Adenosine Triphosphate Immediate source of energy that powers cellular work
  9. 9. Phosphates bonds are so fragile V t bl- Very unstable
  10. 10. When ATP is hydrolyzed, it releases free energyenergy Th ll l th tThe cell couples the energy to endergonicendergonic processprocess by transferring a phosphate group from ATP to somephosphate group from ATP to some other molecule PHOSPHORYLATIONPHOSPHORYLATION Phosphorylated intermediate- morePhosphorylated intermediate more reactive (less stable)
  11. 11. -Aerobic respiration -FermentationFermentation
  12. 12. “The wholesale release of energy from fuel is difficult to harness efficiently for i k”constructive work” Cellular respiration does not oxidize glucose in one step
  13. 13. Three metabolic stages 1. Glycolysisy y › Cytosol › Breakdown of glucose into 2 molecules of pyruvate 2. Krebs cycle › Mitochondrial matrix › Decomposes pyruvate into CO› Decomposes pyruvate into CO2 3. Electron Transport chain and oxidative phosphorylationphosphorylation › Inner membrane of mitochondria
  14. 14. Substrate phosphorylationphosphorylation › When any enzyme transfers a phosphate group from a substrate to ADPADP
  15. 15. Oxidative phosphorylation › Electrons are passed from one electron acceptor› Electrons are passed from one electron acceptor to another › Energy released at each step is used to make ATP › Accounts for 90% of ATP generated
  16. 16. 1. Energy investment Phasegy 2. Energy payoff phase
  17. 17. Glucose enters the cell DEBIT: 2 ATP molecules Ready for splitting
  18. 18. Downhill reaction S b t t h h l ti Water extraction forms double bond Substrate phosphorylation
  19. 19. Aka Citric Acid Cycley
  20. 20. •Occurs in the inner membrane of mitochondria
  21. 21. Inc electronegativityInc electronegativity Final electron acceptoracceptor
  22. 22. ETC makes no ATP directly How does the mitochondrion couple ETC and energy release to ATP synthesis?gy y CHEMIOSMOSIS
  23. 23. H+ gradient couples the redox reactions of ETC to ATP synthesis PROTON MOTIVE FORCE
  24. 24. NADH- 3 pumps= 3 ATPsNADH 3 pumps= 3 ATPs FADH2 – 2 pumps= 2 ATPs
  25. 25. Fermentation enables some cells toFermentation enables some cells to produce ATP without the use of oxygen Cellular respiration › Relies on oxygen to produce ATPyg p In the absence of oxygenyg › Cells can still produce ATP through fermentation
  26. 26. GlycolysisGlycolysis › Can produce ATP with or without oxygen, in aerobic or anaerobic conditionsaerobic or anaerobic conditions › Couples with fermentation to produce ATP
  27. 27. Fermentation consists ofFermentation consists of › Glycolysis plus reactions that regenerate NAD+, which can be reused by glyocolysiswhich can be reused by glyocolysis
  28. 28. In alcohol fermentation › Pyruvate is converted to ethanol in two steps, one of which releases CO2
  29. 29. D i l ti id f t tiDuring lactic acid fermentation › Pyruvate is reduced directly to NADH to form lactate as a waste productlactate as a waste product
  30. 30. Both fermentation and cellular respiration › Use glycolysis to oxidize glucose and other organic fuels to pyruvate
  31. 31. Fermentation and cellular respiration › Differ in their final electron acceptor Cellular respiration › Produces more ATP
  32. 32. • Pyruvate is a key juncture in catabolism• Pyruvate is a key juncture in catabolism Glucose CYTOSOL Pyruvate No O2 present O presentNo O2 present Fermentation O2 present Cellular respiration Ethanol or lactate Acetyl CoA MITOCHONDRION CitricCitric acid cycle Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 9.18
  33. 33. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
  34. 34. Comparison of ETC in Photosynthesis and RespirationRespiration
  35. 35. Mitochondria ChloroplastMitochondria Electrons from food molecules (oxidation Chloroplast Do not need food to make ATPmolecules (oxidation of food molecules) make ATP light drives theg electron flow down an ETC and H+ gradient formationformation.

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