Warm Up 10/7

 Cellular Respiration outline 

Anaerobic (2 ATP, without oxygen) - glycolysis -> lactic acid fermentation OR alcoholic fermentation
Aerobic (38 ATP, with oxygen) - glycolysis -> pyruvate oxidation -> Krebs cycle -> electron transport chain

Glycolysis (2 ATP)
1. Phosphorylation
- addition of a phosphate group
- 2 phosphate groups added to glucose to form hexose biphosphate (provided by 2 ATP molecules)

2. Lysis
- hexose biphosphate splits to form 2 triose phosphate

3. Oxidation
- 2 hydrogen atoms removed from each triose phosphate
- energy released is used to link on another phosphate group, producing a 3-carbon compound carrying 2 phosphates
- NAD+ is the hydrogen carrier

4. ATP Formation
- pyruvate formed by removing 2 phosphates and passing them to ATP

Krebs Cycle
1. acetyl CoA is combined with oxaloacetate to form a molecule of citrate 
2. hydroxyl group and a hydrogen molecule are removed from the citrate structure in the form of water.  The two carbons form a double bond until the water molecule is added back
3. isocitrate molecule is oxidized by a NAD molecule.  The NAD molecule is reduced by the hydrogen atom and the hydroxyl group. NAD binds with a hydrogen atom and carries off the other hydrogen atom leaving a carbonyl group.  This structure is very unstable, so a molecule of CO₂ is released creating alpha-ketoglutarate.
4. coenzyme A returns to oxidize the alpha-ketoglutarate molecule.  A molecule of NAD is reduced again to form NADH and leaves with another hydrogen.  This instability causes a carbonyl group to be released as carbon dioxide and a thioester bond is formed in its place between the former alpha-ketoglutarate and coenzyme A to create a molecule of succinyl-coenzyme A complex
5. free-floating phosphate group displaces coenzyme A and forms a bond with the succinyl complex.  The phosphate is then transferred to a molecule of GDP to produce an energy molecule of GTP.  It leaves behind a molecule of succinate.
6. succinate is oxidized by a molecule of FAD (Flavin adenine dinucleotide).  The FAD removes two hydrogen atoms from the succinate and forces a double bond to form between the two carbon atoms, thus creating fumarate.
7. An enzyme adds water to the fumarate molecule to form malate.   The malate is created by adding one hydrogen atom to a carbon atom and then adding a hydroxyl group to a carbon next to a terminal carbonyl group.
8. Malate molecule is oxidized by a NAD molecule.  The carbon that carried the hydroxyl group is now converted into a carbonyl group.  The end product isoxaloacetate which can then combine with acetyl-coenzyme A and begin the Krebs cycle all over again.

Electronic Transport Chain

- electrons are transported to meet up with oxygen from respiration at the end of the chain
- the overall electron chain transport reaction is:
2 H⁺ + 2 e⁺ + 1/2 O₂ ---> H₂O + energy
- 2 hydrogen ions, 2 electrons, and an oxygen molecule react to form as a product water with energy released in an exothermic reaction.
- energy released is coupled with the formation of three ATP molecules per every use of the electron transport chain.