FATES OF PYRUVATE -Depends upon presence or absence of O 2 - Anaerobic conditions: 1)alcohol fermentation – pyruvate converted to ethyl alcohol 2)lactic acid fermentation - pyruvate converted to lactic acid (cheese, yogurt) - Aerobic conditions: Pyruvate enter the mitochondria where it is completely oxidized Pyruvate -> enzyme -> acetyl group + CO 2 + NADH (3C) (pyruvate (2C) dehydrogenase) From 2 pyruvates: 2 acetyl fragments 2 CO 2 exhaled 2 NADH Acetyl fragment joins Coenzyme A (CoA) and enters Krebs Cycle in mitochondrial matrix

We end up with what we start off with 1 turn of the cyclefrom glucose oxidation reactions decarboxylations ATP reduced NADH reduced FADH2

Energy Yield So Far… Glycolysis: –2 ATP, 2 NADH Pyruvate Oxidation: –2 NADH, 2 CO 2 Krebs Cycle: –2 ATP –6 NADH –2 FADH 2 –4 CO 2

Electron Transport Complexes Only 3 sites that can pump protons; II can’t Complex I – NADH Dehydrogenase Takes H off NADH; conducts e- from NADH to ubiquinone Complex II – succinate dehydrogenase – conducts e- from FADH 2 to ubiquinone Complex III – cytochrome BC1 – conducts e- from ubiquinone – cytochrome C Complex IV – cytochrome oxidase – conducts e- from cytochrome – O 2, THE FINAL ELECTRON ACCEPTOR

Adding up the ATP Glycolysis 2 ATP Krebs2 ATP 10 NADH x 3 ATP/NADH30 ATP 2 FADH 2 x 2 ATP/FADH 2 4 ATP

Control of ATP Synthesis Controlled by energy needs of the cell Enzymes in Glycolysis and Krebs control this