1. Topic 8.2 Chap. 7 in Falcon Book
Cell Respiration
Topic 8.2
Chap. 7 in Falcon Book

2. 8.2 Cell Respiration Oxidation (8.2.1) Reduction
Loss of electrons from an element
Oxygen is gained
Hydrogen is lost
OIL – Oxidation is Loss of energy
Reduction
Gain of electrons from an element
Oxygen is lost
Hydrogen is gained
RIG – Reduction is Gain of energy

3. Cell Respiration
Occurs in the mitochondria of animal cells
Reactants are glucose and oxygen; products are water and carbon dioxide
Aerobic respiration occurs in three steps:
Glycolysis
Krebs Cycle (aka Citric Acid Cycle)
Oxidative Phosphorylation (aka Electron Transport Chain)

4. Glycolysis Occurs in the cytoplasm, just outside of the mitochondria
Begins with phosphorylation:
2 ATP lose a phosphate to glucose (a six carbon sugar) and thus become ADP
The added phosphates makes the sugar unstable, thus allowing it to be broken down more easily

5. Glyceraldehyde-3- phosphate
After phosphorylation is lysis
six carbon glucose is broken down into two three-carbon molecules called G3P
Glyceraldehyde-3- phosphate
G3P is oxidized
results in the production of two triose phosphate molecules and two NADH molecules
2 NAD+ 2

6. Substrate level phosphorylation of ATP
4 ADP  4 ATP

7. G3P
G3P

8. Glycolysis Summary 2 ATP used at start
Total of 4 ATP’s produced. Net gain of 2
2NADH are produced
2 Pyruvates are produced
Phosphorylation, lysis, oxidation
Controlled by enzymes, increase in ATP levels will result in end product inhibition and slow or stop process.

9. 8.2 Anaerobic Respiration (no oxygen present)
pyruvate will be converted to lactic acid (animals) or ethanol and carbon dioxide (yeast)
Aerobic Respiration (oxygen present)
pyruvate will go into the mitochondria to participate in the Kreb’s Cycle

10. 8.2
The fluid filled matrix contains the enzymes necessary for the Krebs cycle to take place

11. Link Reaction
Once inside the matrix of the mitochondria (via active transport) each pyruvate is decarboxylated (CO2 is removed)
The remaining two-carbon molecule (acetyl) reacts with reduced co-enzyme A (carbohydrate metabolism only), and at the same time NADH + H+ is formed

13. Krebs Cycle
Each acetyl group (CH3CO)(2C) combines with oxaloacetate(4C) with the removal of Coenzyme A (CoA) to make citrate (6C) a.k.a. citric acid

14. Citrate(6C) is oxidized and a carbon is lost to become CO2
Result is a compound called
a-ketoglutarate (5C)

15. a–ketoglutarate is oxidized and another carbon is lost to make carbon dioxide, thus leaving succinate (4C)molecule. NAD+ is reduced to NADH

16. This Succinate (4C) molecule goes through a series of reactions in which hydrogens are removed then collected by hydrogen carrying coenzymes such as FADH2 and NADH. One ATP is created from ADP + Pi
The final molecule left at the end of the cycle is called oxaloacetate (4C)

18. In summary, one turn of the krebs cycle yields:
2 CO2
3 NADH + H+
1 FADH2
1 ATP

20. Krebs Cycle Review
Krebs Cycle will run twice for each glucose molecule entering cellular respiration!
Totals from one Glucose molecule
4 CO2
6 NADH + H+
2 FADH2
2 ATP

21. Oxidative Phosphorylation (chemiosmosis)
Third and final step of cellular respiration
Electron transport carriers (proteins)are strategically arranged over the inner membrane of the mitochondrian (called the electron transport chain)
Electrons get passed through a series of proteins of increasing electronegativity
The final electron acceptor is oxygen(high electronegativity) which then binds with hydrogen to form water
As these carriers oxidize NADH + H+ and FADH2 (products of the Krebs cycle), energy is released

23. This energy forces hydrogen ions to move across the concentration gradient from the mitochondrial matrix (inner portion) to the space between the two membranes (intermembrane space)

24. Oxidative Phophorylation Animation
Eventually the hydrogen ions flow back into the matrix through protein channels in specialized molecules called ATP Synthase
As the ions flow down the gradient (via the ATP Synthase protein channels) energy is released and ATP is made
Oxidative Phophorylation Animation

26. Structure and Function of Mitochondria
The mitochondria is specially designed to promote efficiency of respiration:
Membranes fold in upon themselves to form cristae
Cristae provide a larger surface area for the electron transport chain
The space between the outer and inner membranes provides room for the accumulation of hydrogen ions