1. Big Campbell ~ Ch 8,9,10 Baby Campbell Ch 6,7,8
UNIT IV – CELL ENERGY
Big Campbell ~
Ch 8,9,10
Baby Campbell
Ch 6,7,8

2. I. THE WORKING CELL Energy Kinetic Energy Potential Energy
Chemical Energy

3. I. THE WORKING CELL, cont Thermodynamics First Law of Thermodynamics
Total amount of energy in universe is constant
Second Law of Thermodynamics
Energy is lost to the environment as heat; that is, some energy becomes unusable

4. I. THE WORKING CELL, cont Metabolism Two types of reactions Exergonic
Endergonic 4

5. I. THE WORKING CELL, cont
Gibbs Free Energy (ΔG)

6. I. THE WORKING CELL, cont
ΔG and Enzyme Catalysis

7. I. THE WORKING CELL, cont Energy Coupling
Energy released in exergonic rxn is used to drive endergonic rxn.

8. II. ATP Adenosine Triphosphate
Nucleotide that stores & provides usable energy to the cell
Structure of ATP
ATP contains potential energy, especially between 2nd and 3rd phosphate groups.
P ~ P bond is unstable
Easily broken by 8

9. II. ATP, cont
ATP → ADP + Pi
Coupled with endergonic rxn – specifically, by transferring phosphate group from ATP to another molecule.

10. II. ATP, cont ADP + Pi → ATP Mechanisms for “making” ATP
Substrate-level Phosphorylation
Oxidative Phosphorylation
Photophosphorylation

11. II. ATP, cont Substrate-Level Phosphorylation
Oxidative Phosphorylation /
Photophosphorylation

12. III. ENERGY IN THE CELL Oxidation-Reduction Reactions
Energy yield in catabolism comes from transfer of electrons
Movement of electrons releases chemical energy of molecule
Released energy used to generate ATP from ADP and Pi
Known as redox reaction
Oxidation
Reduction

13. III. ENERGY IN THE CELL, cont
Oxidation-Reduction Reactions, cont
Electron movement in molecules often traced by changes in H atom distribution

14. III. ENERGY IN THE CELL, cont
Importance of Electron Carriers
Energy contained in molecules (for example, glucose) must be released in a series of steps
Electrons released as hydrogen atoms with corresponding proton
Hydrogen atoms are passed to an electron carrier
Electron carriers are coenzymes
“Carry” 2 electrons in the form of H-atoms
Allow for maximum energy transfer, minimum energy loss

15. III. ENERGY IN THE CELL, cont
Electron Carriers
NAD+
Electron acceptor in cellular respiration
Reduced to
FAD
Electron acceptor in Krebs Cycle
NADP+
Electron acceptor in light reaction of photosynthesis

16. IV. ♪ ♫ THE CYCLE OF LIFE ♪ ♫
Photosynthesis
Cellular Respiration

17. V. PHOTOSYNTHESIS – AN OVERVIEW
Photosynthesis – Process of capturing ___________ energy and converting it to ________________ energy
Plants are __________________; also known as _____________
Redox Reaction 17

18. V. PHOTOSYNTHESIS – AN OVERVIEW, cont

19. V. PHOTOSYNTHESIS – AN OVERVIEW, cont
Chloroplast Structure
Thylakoids –
Site of Light Reaction
First step in photosynthesis
Granum
Stroma
Site of Calvin Cycle
Second step in photosynthesis

20. VI. LIGHT REACTION OF PHOTOSYNTHESIS
Occurs in thylakoid membranes
Converts light energy to chemical energy
Light energy
Visible light is a small portion of the electromagnetic spectrum.
Light absorbed by chlorophyll and other photosynthetic pigments to power reactions is not seen. Light not utilized by plant is reflected & seen by human eye.
Light energy measured in photons. 20

21. VI. LIGHT REACTION OF PHOTOSYNTHESIS, cont
Photosynthetic Pigments
Chlorophyll a – absorbs mainly blue-violet and red light
Chlorophyll b – absorbs mainly blue and orange light
Carotenoids – other accessory pigments; expand spectrum of light energy that can be used for photosynthesis

22. VI. LIGHT REACTION OF PHOTOSYNTHESIS, cont
A photon of light energy is absorbed by pigment molecule in Photosystem II.
Energy is passes from one molecule to another until it reaches P680 - pair of chlorophyll a molecules.
Electron in each is excited to higher energy state – transferred to primary electron acceptor.
Water is split to replace electron lost by P680. O2 is released. H+ ions remain. 22

23. VI. LIGHT REACTION OF PHOTOSYNTHESIS, cont
Excited electron moves from primary electron acceptor to Photosystem I via electron transport chain. As electron “falls”, energy is released. Used to synthesize ATP through chemiosmosis.
Known as photophosphorylation

24. VI. LIGHT REACTION OF PHOTOSYNTHESIS, cont
Light energy is transferred via light-harvesting complexes to P700 in Photosystem I.
Excited electron is captured by primary electron acceptor. P700’s electron is replaced by electron transport chain on Photosystem II.
Electron from P700 moves through a short electron transport chain, reducing NADP+ to NADPH. 24

25. VI. LIGHT REACTION OF PHOTOSYNTHESIS, cont
Linear Electron Flow 25

26. VII. CALVIN CYCLE OF PHOTOSYNTHESIS
Also known as Dark Reaction, Light-Independent Rxn
Occurs in stroma of chloroplasts
“Synthesis” part of photosynthesis; utilizes ATP, NADPH generated in Light Reaction + CO2 to produce organic molecules
Anabolic; endergonic
Requires enzyme Rubisco
Three basic steps
Carbon Fixation
Reduction
Regeneration of RuBP 26

27. VII. CALVIN CYCLE OF PHOTOSYNTHESIS, cont27

28. VIII. PHOTORESPIRATION
Counterproductive pathway that produces 2-C molecule, which is then released as CO2
Due to oxygen competing for active site of Rubisco
Consumes ATP; decrease carbohydrate yield

29. VIII. PHOTORESPIRATION, cont
Plant Adaptations
C4 Plants

30. VIII. PHOTORESPIRATION, cont
Plant Adaptations, cont
CAM Plants

31. IX. CELLULAR RESPIRATION – AN OVERVIEW
Process used by cells to convert chemical energy in glucose (and other molecules) to ATP
Primarily takes place in mitochondria of eukaryotic cells
Overall Reaction

32. IX. CELLULAR RESPIRATION OVERVIEW, cont
Glycolysis
“Sugar-breaking”
Initial breakdown of glucose to intermediate, some ATP
Pyruvate Oxidation
Occurs in mitochondria
Krebs Cycle
Completes oxidation of glucose to CO2
Produces ATP, but more importantly provides high-energy electrons for etc
Electron Transport Chain
Oxidative Phosphorylation
Highest ATP yield; uses energy released from downhill flow of electrons to generate ATP

33. X. GLYCOLYSIS Occurs in cytosol of cell Does not require oxygen
First part of pathway is energy investment phase
Second part of pathway is energy pay-off phase
Energy Investment Phase

34. X. GLYCOLYSIS, cont
Energy Pay-Off Phase

35. X. GLYCOLYSIS, cont
Summary of Glycolysis

36. XI. OXIDATIVE RESPIRATION
Pyruvate Oxidation
Oxygen must be available
Takes place in mitochondrial matrix prior to Citric Acid Cycle …
Carboxyl group of pyruvate is removed, given off as CO2
Remaining 2-C molecule is oxidized to acetate → NAD+ reduced to NADH + H+
Acetate binds to molecule known as Coenzyme A to form acetyl CoA

37. XI. OXIDATIVE RESPIRATION, cont
Citric Acid Cycle (Krebs cycle, tricarboxylic acid cycle, TCA cycle)
2-C molecule goes through a series of redox rxns.
Occurs in mitochondrial matrix
Produces NADH, FADH2, ATP, and CO2.
CoA is not actually a part of the reaction it is recycled remember, it is an enzyme!

38. XI. OXIDATIVE RESPIRATION, cont
Oxidative Phosphorylation
Traditionally called Electron Transport
Occurs in inner mitochondrial membrane
Membrane organized into cristae to increase surface area
Two components to Oxidative Phosphorylation
Electron Transport Chain
Chemiosmosis

39. XI. OXIDATIVE RESPIRATION, cont Oxidative Phosphorylation
Electron Transport Chain
Collection of molecules, each more electronegative than the one before it
Molecules are reduced, then oxidized as electrons are passed down the chain
Oxygen is ultimate electron acceptor
Purpose is to establish H+ gradient on two sides of inner mitochondrial membrane
Energy from “falling electrons” used to pump H+ from matrix into intermembrane space

40. XI. OXIDATIVE RESPIRATION, cont Oxidative Phosphorylation
Chemiosmosis
Enzyme complexes known as ATP synthases located in inner mitochondrial membrane
H+ electrochemical gradient provides energy
Known as proton motive force
Movement of H+ ions through membrane rotates enzyme complex
Rotation exposes active sites in complex
ATP is produced from ADP and Pi

41. XI. OXIDATIVE RESPIRATION, cont
A summary of oxidative phosphorylation . . .

42. XII. CELLULAR RESPIRATION – A SUMMARY
Each NADH shuttled through ETC results in approximately _________ ATP
Each FADH2 shuttled through ETC results in approximately _________ ATP.
Total ATP Gain in Cellular Respiration =
____ (glycolysis) + ____ (citric acid cycle) + ____ (oxidative phosphorylation) = _____ ATP / glucose

43. XII. CELLULAR RESPIRATION – A SUMMARY, cont

44. XII. CELLULAR RESPIRATION – A SUMMARY, cont
Regulation 44

45. XIII. CATABOLISM OF OTHER FOOD MOLECULES

46. XV. FERMENTATION Anaerobic pathway Glycolysis Occurs in cytosol
Purpose →
Glycolysis

47. XV. FERMENTATION, cont

48. XV. FERMENTATION, cont