1. Cell Respiration The process by which cells turn food molecules into cell energy

2. The Complete breakdown of foods occurs in aerobic respiration The general reaction of aerobic respiration is: glucose + O 2  CO 2 + H 2 O + ATP + heat This reaction occurs in steps: –Glycolysis –Transition reaction –Krebs Cycle –Electron Transport Chain

3. Glycolysis Occurs in the cytoplasm Splits a 6-carbon sugar into 2 x 3-C pyruvates Reaction sequence: Sugar (6C)  2 Pyruvates (3C) Produces: –2 ATP molecules –2 NADH 2

4. Transition reaction Processes pyruvate so that it can enter mitochondrion The reaction sequence: 2 pyruvate (3C)  2 acetyl (2C) Produces: –2 NADH 2 2 acetyl groups easily enter the mitochondrion of the cell

5. Transition between cytoplasm and mitochondrion

6. Krebs Cycle Occurs in the cytoplasm of the mitochondria (stroma) Cyclical series of reactions which breaks down acetyls releasing CO 2 Produces: –2 ATP’s –6 NADH 2 –2 FADH 2

7. Up to this point, the entire molecule of glucose has been broken down to form 6 CO 2 ’s Yet, only 4 ATP’s have been formed during: Glycolysis Transition & Krebs Cycle Potential energy of NADH2 and FADH2 can be released in Electron Transport Chain

8. Electron Transport Chain – harvests potential energy of NAD and FAD coenzymes Occurs along inner membrane (cristae) of mitochondrion

9. Overall Energy Harvest of Aerobic Cell Respiration Much more ATP than the 4 molecules received through Gly, Trans, and Krebs!!

10. We metabolize more than sugars!!

11. Can cells produce ATP without oxygen being present? Oxygen removes e-’s from the Electron Transport Chain to help make ATP If oxygen is not present, NADH 2 must be oxidized to NAD + to allow cells to make ATP

12. Animal cells engage in fermentation Fermentation allows NAD+ to be recycled Fermentation produces 2 ATP’s per molecule of glucose broken down Glucose is not completely broken down

13. Plant and fungal cells engage in fermentation This process also allows NAD+ to be recycled Produces 2 ATP’s per molecule of glucose broken down Glucose is not completely broken down

14. Fermentations produce many foods and drinks! Dairy fermentations –Cheeses –Yogurts –Sour cream Fermented foods –Breads –Tofu and tempeh –Pickles, sauerkraut Fermented beverages –Wines, beers, ales