Energy Releasing Pathways C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + ATP

1. Energy Releasing PathwaysC6H12O6 + 6O2 6CO2 + 6H2O + ATP • (Harvesting Chemical Energy) • Glycolysis • Fermentation • Aerobic respiration

3. Begins with the biochemical pathway glycolysis. • Glycolysis animation • http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__how_glycolysis_works.html • Redox Reaction • Oxidation: loss of e- (glucose) • Reduced: Gain of e- (Co2)

4. Glycolysis • Takes place in the cytosol • 1, 6 carbon molecule of glucose goes through a series of chemical reactions catalyzed by specific enzymes to produce 2, 3 carbon molecules of pyruvic acid. • NAD+ similar to NADP+ • NAD+ carry electrons and Hydrogen ions (NADH)

5. Glycolysis

6. Glycolysis • 1 Glucose 2 Pyruvic acid • 2 ATP 4 ATP • 2 NAD+ 2 NADH • 4 ADP + 2Phospates • Net 2 ATP

7. What Next? Organic Compound Glycolysis ATP no oxygen oxygen Fermentation Aerobic Respiration

8. FermentationAnaerobic Respiration • Prokaryotes and protists in anaerobic habitats (mainly unicellular organisms) • Does not produce ATP • Many Fermentation pathways differ in the types of enzymes and final products produced • Two most common produced are lactic acid and ethyl alcohol

9. Lactic Acid Fermentation • Occurs in muscle cell when strenuous exercise causes muscle cells to use up all the oxygen available to them. They switch to anaerobic respiration and lactic acid builds up in the cells, changing the acidity of the cytoplasm. • Increased acidity decreases the cells ability to contract causing cramps and fatigue. • Eventually it diffuses out of cell into blood stream and is transported to liver where it is converted back into pyruvic acid. • Used to make cheese and yogurt

10. Lactic Acid Fermentation

11. Alcoholic Fermentation • Used by some plants and unicellular organisms such a yeast • Bread making

12. Fermentation Animation • http://www.cst.cmich.edu/users/schul1te/animations/fermentation.swf

13. Aerobic Respiration • Requires O2 • Approximately 20 times as much ATP produced then glycolysis • Two major stages: Krebs cycle and the electron transport chain • In eukaryotic cell takes place in the mitochondria. • Krebs cycle occurs in the mitochondrial matrix • Electron transport chain occurs in the inner membrane

14. Mitochondrion

15. Transition Reaction • Pyruvic acid enters the mitochondrial matrix • It reacts with a molecule called coenzyme A (CoA) to form acetyl CoA • CO2 and NADH and H+ are produced

16. The Krebs CycleAnimationhttp://www.1lecture.com/Biochemistry/How%20the%20Krebs%20Cycle%20Works/index.html

17. The Krebs CycleFive Main Steps Step 1: Acetyl CoA combines with Oxaloacetic acid to form citric acid (regenerates CoA) Step 2: Citric acid releases CO2 and a H atom that combines with NAD+ to form NADH + H+ to form 5 carbon compound. Step 3: 5 carbon compound releases CO2 and a Hydrogen atom (combines with NAD+ to form NADH + H+) to form a 4 carbon compound. A molecule of ATP is formed.

18. Krebs Cycle • Step 4: 4 Carbon compound releases a hydrogen atom ( combines with FAD to Form FADH2) and is converted to another 4 carbon compound. • Step 5: The 4 carbon compound releases a hydrogen atom and is (combines with NAD+ to form NADH + H+)converted back into Oxaloacetic acid.

19. What is Produced? • 1 glucose molecule = 2 turns of the Krebs cycle • 6 NADH • 2 FADH2 • 2 ATP • 4 CO2

20. The Krebs Cycle • Most of the energy from glucose still have not been transferred to ATP • 10 NADH and the 2 FADH2 produced so far to drive the electron transport chain

21. Electron transport ChainAnimation http://www.science.smith.edu/departments/Biology/Bio231/etc.html

22. Energy Yield