1. The Kreb’s Cycle and Electron Transport Chain Biology 112

2. The End of Glycolysis  Only 10% of the energy available in glucose has been used  The rest is still contained in pyruvic acid  The remainder of the energy needs oxygen for the final phases of cellular respiration  These pathways are said to be aerobic

3. The Kreb Cycle  Steps of this process:  Pyruvic acid enters the mitochondrion  One of the three carbons becomes part of a carbon dioxide molecule  The remaining two carbon molecules attach to a coenzyme and form citric acid  The citric acid breaks down, releasing more carbon dioxide  Energy is released in the form of NADH

4. The Kreb’s Cycle - cont  Citric acid turns into a five carbon molecule which then releases another carbon atom to form more carbon dioxide  NADH and ATP is also released  The four carbon molecule remaining will be picked up and used again in the cycle  NADH and FADH 2 (another energy releasing molecule) is released

5. The Electron Transport Chain  NADH and FADH 2 enter the electron transport chain to be used to generate ATP from ADP  It is composed of carrier proteins embedded in the mitochondria (eukaryotes) or cell membrane (prokaryotes)  The end of the chain releases water

6. Adding Up the ATP  By the end of cellular respiration – 36 ATP molecules will have been produced from one molecule of glucose  The cell can generate energy from more than just glucose  Any energy not used by the cell is released as heat

7. Quick and Long Term Energy  Overall, a small amount of ATP is produced by cellular respiration  After a few moments of intense activity, for instance, lactic acid fermentation produces necessary ATP for energy  Lactic acid will require oxygen in order to be broken down  The body stores more energy in the form of the carbohydrate glycogen  After this is used, fats and other molecules are utilized

8. Photosynthesis vs. Respiration PhotosynthesisRespiration FunctionRequires energyReleases energy LocationChloroplastsMitochondria ReactantsCO 2 + H 2 OC 6 H 12 O 6 + O 2 ProductsC 6 H 12 O 6 + O 2 CO 2 + H 2 O