1. Respiration!
Chapter 9~
Cellular Respiration: Harvesting Chemical Energy
Great Animation (show at end too)

2. Big Picture!
Big Picture: Glucose has Stored Energy, Cells must Convert it to ATP (the fuel of the cell)
This happens through a series of energy releasing redox reactions that we will learn about shortly.
Overall Equation for cellular respiration:
C6H12O6 + 6O2 ---> 6CO2 + 6H2O + E (ATP + heat)

3. Redox reactions Oxidation-reduction
Oxidation (i.e. to be oxidized) is e- loss;
Or oxygen gain
Reduction (i.e. to be reduced) is e- gain;
Or hydrogen atom gain
LEO GER
Redox reactions release energy!!!

4. Cellular respiration
Cell Respiration = the controlled release of energy from organic compounds in cells to form ATP!
STAGES:
Glycolysis: location: cytoplasm
Link Reaction:
Krebs Cycle: location mitochondrial matrix
Electron Transport Chain location: inner membrane of mitochondrion

5. Glycolysis Overall: 1 Glucose (6C)2 pyruvate molecules (3C each)
10 total steps but we will focus on 4 stages:
Phosphorylation
cell uses ATP to phosphorylate hexose sugar (glucose) making a Hexose biphosphate
Lysis
Hexose is split in half to make two triose sugars
Oxidation
Each triose loses electrons and hydrogens
These are transferred to NAD+ to make NADH and H+
ATP formation
ATP is produced by substrate-level phosphorylation
2 Pyruvates are made.
2 inorganic phosphates
Animation

6. Glycolysis continued
Net energy yield per glucose molecule: 2 ATP plus 2 NADH + H+;
Note: occurs aerobically or anaerobically; also no CO2 is released

7. For Reference: The 10 steps of Glycolysis

9. Glycolysis can occur aerobically or anaerobically
After Glycolysis…
Glycolysis can occur aerobically or anaerobically
Aerobic Respiration=
Requires oxygen
Occurs in mitochondrion
Pyruvate broken down into
CO2 and H2O
Large yield of ATP
Anaerobic Respiration=
No oxygen
Occurs in cytoplasm
Pyruvate converted to either
lactate OR ethanol and CO2
No further yield of ATP

10. The Next Slides deal with Aerobic Respiration …
Aerobic Respiration Steps:
Link Reaction
Krebs Cycle (Citric Acid Cycle)
Electron Transport Chain (ETC)

11. The link reaction Each pyruvate is converted into acetyl CoA
CO2 is released; (pyruvate is decarboxylated)
NAD+  NADH + H+
Note: NAD+ gets reduced
NADH is an electron carrier

12. Krebs/Citric Acid Cycle
From this point, for each turn, 2 C atoms enter (acetyl CoA) and 2 exit (carbon dioxide)
Oxaloacetate is regenerated (the “cycle”)
For each acetyl CoA that enters:
3 NAD+ reduced to 3 NADH;
1 FAD reduced to FADH2
1 ATP molecule produced

13. Electron transport chain
The ETC carries electrons from carrier molecules (NADH & FADH2) down to oxygen (the final electron acceptor!)
The ETC pumps H+ into the intermembrane space!
ATP synthase: produces ATP by using the H+ gradient as H+ flows back into the matrix
Chemiosmosis: The production of ATP using the energy of hydrogen ion (proton) gradients across membranes.
This whole process of making ATP is also called oxidative phosphorylation (b/c it uses oxygen as the final electron acceptor)
OXYGEN is the final electron acceptor. It gets reduced to make H2O

14. Electron Transport
NADHFMN iron sulfur protein (FeS) a lipid called ubiquinone (Q) cytochromes O2
FADH2 starts donating its electrons to the iron sulfur protein. Therefore it is able to make less ATP than NADH.
ATP synthase animation
ATP

15. Review: Cellular Respiration
Glycolysis
2 ATP (substrate-level phosphorylation)
Kreb’s Cycle: ATP (substrate-level phosphorylation)
Electron transport & oxidative phosphorylation:
32-34 ATP as follows:
10 NADH used to make 30ATP
2 FADH2 used to make 4 ATP
38 TOTAL ATP/glucose
Great Animation

16. The Mighty MITOCHONDRION! (draw and label)

17. Mitochondria (Structure and function)
Cristae
Small space between inner and outer membranes
Fluid matrix

18. What if there’s no oxygen? (anaerobic respiration)
Glycolysis
Fermentation:
alcohol~ pyruvate is converted to ethanol and CO2 (in yeast and bacteria)
lactic acid~ pyruvate is converted to lactate (in animals)

19. Why Fermentation? *Fermentation allows glycolysis to continue
It recycles NAD+ (a necessary oxidizing agent required for the continuation of glycolysis)
see next slide for review of glycolysis…

20. 2 inorganic phosphates

21. End of IB
The next slides are interesting but not in the syllabus

22. What if there’s no Glucose?
Respiration still can continue
Beta-oxidation: lipid catabolism to acetyl CoA.
Amino acids
Converted to intermediates in glycolysis and Krebs cycle

23. Control of Respiration
Feedback Inhibition
Examples
Phosphofructokinase (Enzyme 3 in Glycolysis)
allosterically inhibited by ATP
Allosterically activated by AMP (derived from ADP)
Why?

24. Oxidizing agents in respiration
NAD+ (nicotinamide adenine dinucleotide)= initial electron acceptor (oxidizing agent)
NAD + is reduced to NADH
Oxygen is the eventual e- acceptor (The ULTIMATE Oxidizing Agent)

25. Facultative anaerobes don’t require oxygen but can live with it
Facultative anaerobes don’t require oxygen but can live with it. (yeast/bacteria)
Obligate anaerobes
Can’t live with oxygen
Clostridium botulinum (botulism bacterium)