1. Chapter 9 CELLULAR RESPIRATION

3. Relationship of Processes
Respiration: exergonic (releases E) C6H12O6 + 6O2  6H2O + 6CO2 + ATP (+ heat) Photosynthesis: endergonic (requires E) 6H2O + 6CO2 + Light  C6H12O6 + 6O2

4. location: mitochondrial cristae
Cellular Respiration
complex process whereby cells make ATP by breaking down organic compounds(glucose)
many rxns in aerobic respiration are redox: (one reactant is oxidized while another is reduced)
location: mitochondrial cristae

5. Oxidation and Reduction
loses e- (donor) gains e- (acceptor) Not all electrons are transferred from one substance to another, some change the degree of e- sharing in covalent bonds.

6. Glucose Catabolism
Catabolic Pathway Complex organic Simpler waste molecules products with less E Some E used to do work and dissipated as heat Oxygen is extremely electronegative Oxidation of glucose transfers e- to lower energy state- does main work of respiration releases energy to make ATP ** done in series of steps**

7. Moving Electrons Electron Carriers
Electrons cannot move alone in cells
Move as part of H atom
Energy is released as electrons “fall” from organic molecule to O2.
Electron Carriers
Move electrons by shuttling H atoms around
NAD+  NADH
FAD+2  FADH2

8. NAD+ Coenzyme (nicotinamide adenine dinucleotide)
Electron acceptor- carries electrons to ETC
Acts as an oxidizing agent during respiration
Dehydroginase(enzyme)- catalyzes NAD+  NADH
NAD animation

9. Electron Transport Chain
ETC breaks the fall of electrons of oxidation of glucose into series of smaller steps
Released energy is used to make ATP
Extra energy is released as heat.

11. Glycolysis (glucose/splitting)
GLUCOSE(6C)is partially oxidized
end products: 2 PYRUVATE(3C), 2 NADH, 2 ATP
- occurs in cytosol
- 1st step: always occurs before respiration or fermentation
- occurs in the absence of oxygen
- ancient pathway (early prokaryotes)
- inefficient

12. Glycolysis Overview Stage 1: Energy Investment
Cell uses ATP to phosphorylate glucose
Endergonic
Stage 2: Energy Payoff
Two 3-C compounds oxidized
Exergonic
Yield
2 pyruvate
2 NADH
2 ATP- substrate-level phosphorylation
- Phosphate comes from sugar substrate(PEP), not ETC

13. Steps of Glycolysis
glycolysis animation

14. 2 Possible Pathways for Pyruvate
If O2 present If no O2 present
respiration fermentation
(aerobic) (anaerobic respiration)
mitochondria cytosol

15. Stages of Cellular Respiration
1. Glycolysis 2. Citric Acid(Krebs)Cycle 3. Oxidative Phosphorylation

16. Cellular Respiration(aerobic)
C6H12O O2  6 H2O + 6 CO ATP
Process of breakdown of pyruvate in the
presence of oxygen
- prokaryotic cells: occurs in cytosol
- eukaryotic cells: occurs in mitochondria
- much more efficient than anaerobic respiration

17. 2 Major Stages of Respiration
1. Citric Acid Cycle
- oxidation of glucose is completed
- NADH and FADH2 are produced
2. Electron transport chain
- NADH is used to make ATP via oxidative phosphorolation
- location where most ATP is made

18. Location of Processes
Citric Acid Cycle (matrix) ETC (inner membrane of cristae)

19. Pyruvate oxidized to Acetyl CoA
Occurs before the Citric Acid Cycle
3 step oxidation process
NAD+ reduced to NADH (acetate formed)
Coenzyme A attached to acetate to form Acetyl CoA
CO2 by-product is released into atmosphere
Pyruvate + CoA + NAD+  Acetyl CoA + CO2 + NADH

20. Citric Acid Cycle (Krebs Cycle)
2 pyruvate from glycolysis enter cycle
Occurs in mitochondrial matrix
Glucose is fully oxidized

21. animation

22. Oxidative Phosphorylation (production of ATP)
Electron Transport Chain
Occurs in inner membrane of mitochondria
Produces ATP by oxidative phosphorylation via chemiosmosis
Chemiosmosis
H+ ions pumped across inner mitochondrial membrane
H+ ions diffuse through ATP synthase to make ATP

23. Electron Transport Chain
Collection of molecules embedded in inner membrane of mitochondria
Tightly bound protein complexes
FADH2 and NADH donate e- for electron transport (redox rxns) for ATP synthesis
Does not make ATP directly, ATP made through chemiosmosis
O2 is final e- acceptor from H+
to form H2O

24. Oxidative Phosphorylation

25. Energy Coupling of Chemiosmosis
How ATP Synthase Works
H+ ions enter stator (1/2 channel) in membrane
H+ ions enter rotor- changes shape of subunits
Rotor spins within membrane
Each H+ ion makes one complete turn
Passes into matrix
Turning of rod produces ATP from ADP and Pi
animation ETC

27. Fermentation = glycolysis + regeneration of NAD+
Lactate Fermentation (animals)
- pyruvate converted to lactate
A. NADH is oxidized and donates its H to pyruvate
B. resultant NAD returns to glycolysis where it is reduced to NADH
C no release of CO2
** 2 ATP formed **
** process is CYCLICAL**
**lactate eventually diffuses into liver where it is converted back to pyruvate when O2 again present **
2. Alcoholic Fermentation (yeasts, plant cells, microorganisms)
- pyruvate converted to ethanol
A. CO2 molecule is removed from pyruvate (3C) forming acetaldehyde
(2 C) B. acetyldehyde is reduced to form ethanol
2 H (from NADH + H ion) are added to 2C compound to form
ethanol
C. NAD is formed (back to glycolysis)
** 2 ATP formed **
** process is CYCLICAL**
**causes alcohol in beer and wine,
air bubbles in bread, beer, and wine**

28. NO ATP FORMED IN FERMENTATION
PURPOSE OF FERMENTATION:
TO REGENERATE NAD FOR GLYCOLYSIS
2 ATP produce enough energy for prokaryotes and small multi-cellular eukaryotes
Useful for anaerobes and facultative anaerobes
Very widespread metabolic pathway of Earth’s organisms

29. Alternative Energy Sources
What if the body runs out of sugar for glycolysis? Can the body still make ATP?
YES
This is how the Atkins and South Beach diets work.
They are low carb, high protein/fat diets.

30. Alternative Energy Sources
Fats as fuel:
Glycerol  PGAL  glycolysis
FA tails  Acetyl CoA  Krebs
Proteins as fuel:
proteins  amino acids
Amino acids  pyruvate or acetyl CoA  Krebs

31. review animation

32. Biofeedback Regulation of Cellular Respiration
Importance of Phosphofructokinase: (regulates rate of respiration)
Allosteric enzyme- receptors for
specific inhibitors and activators
controls rate of glycolysis and citric acid cycle
Inhibited by ATP and citrate
citrate citric acid cycle
ATP glycolysis
Stimulated by AMP
AMP+ P + P ATP

33. Oxidative Phosphorylation
Review of Respiration
Glycolysis
Citric Acid Cycle
Oxidative Phosphorylation
Electron Transport Chain Chemiosmosis