Anaerobic Respiration

1. Anaerobic Respiration

2. During the last stage of cell respiration, electrons from glucose are passed down the electron passport chain to the final electron acceptor, oxygen

3. Chemiosmosis couples the electron transport chain to ATP synthesis:

4. Aerobic Respiration • When oxygen is the final electron acceptor, the process is called aerobic respiration • Aerobic = occurring in the presence of oxygen

5. Anaerobic Respiration • Some prokaryotes are able to carry out anaerobic respiration, respiration in which an inorganic molecule other than oxygen (O2) is the final electron acceptor.

6. What happens if there is no available electron acceptor? Glucose 2 ADP 2 NAD+ glycolysis 2 ATP 2 NADH 2 pyruvate Aerobic respiration: The NADH then passes its high energy e- to the electron transport chain (becoming NAD+ again) and eventually to O2 Anaerobic respiration: Without O2, NADH has nowhere to donate its e- to, NAD+ cannot be regenerated, and glycolysis stops

7. Anaerobic fermentation • Fermentation: An alternative set of reactions that can follow glycolysis in the absence of oxygen as a final electron acceptor. • Extremely inefficient: no Kreb’s cycle, no ETC. Glycolysis produces a net of 2 ATP’s per glucose molecule

8. FERMENTATION PATHWAYS ALLOWS CELLS TO REGENERATE NAD+ FOR GLYCOLSIS Fermentation by-product Intermediate accepts electrons from NADH 2 NAD+ 2 NADH 2 Pyruvate Glucose 2 ATP 2 ADP

9. LACTIC ACID FERMENTATION OCCURS IN HUMANS Pyruvate accepts electrons from NADH 2 Lactate 2 NAD+ 2 NADH Glucose 2 ATP 2 ADP 2 Pyruvate

10. During heavy exercise, ATP production will switch from aerobic respiration to anerobic respiration

11. ALCOHOL FERMENTATION OCCURS IN YEAST 2 CO2 2 Acetylaldehyde 2 Ethanol 2 NAD+ 2 NADH Glucose 2 ATP 2 ADP 2 Pyruvate

12. The Stuff of Life