1. Cellular Respiration Part 3 You are hardcore for learning this!!! You will thank me later

2. Krebs Cycle 2 nd step in cellular respiration Takes place in the mitochondria Uses the pyruvic acid from glycolysis Recall glycolysis takes place in the cytoplasm and breaks down sugar into pyruvic acid Glycolysis also gives sugar’s electrons to ADP to make ATP

3. Krebs Cycle During the Krebs cycle, energy is used to break sugar down into carbon dioxide Can you remember the process when you break a molecule by removing electrons? –Yep! Oxidation. I knew you knew.

4. 1 st step of Krebs Cycle Citric Acid Production Pyruvic Acid (3 Carbon Compound from broken sugar) enter the mitochondria Part of the Pyruvic Acid breaks and forms a carbon dioxide. And is released. The two carbons left over from pyruvic acid become a compound called Acetyl-CoA (CoA means Coenzyme A). –Note: Acetyl-CoA consists of two carbons + the Coenzyme A. Can you remember what an enzyme is?

5. 1 st step of Krebs Cycle Citric Acid Production AND FINALLY.. The moment you’ve all been waiting for: –Citric Acid Production Acetyl-CoA adds four carbon molecules to produce CITRIC ACID!!!!!!!

6. 2 nd Step of Krebs Cycle Energy Extraction Citric Acid (a 6 carbon molecule) is broken down (oxidized) into a 5-carbon compound and then a 4- carbon compound The loss of electrons are captured by electron carriers: NAD + and FAD NAD + and FAD become NADH and FADH 2 The loss of electrons are also captured by ADP to form ATP that can be used directly by the cell.

7. Why so many other electron carriers besides ATP? NADH and FADH2 carry many electrons that can be used to form huge amounts of ATP in the last step of cellular respiration. What happens to that left over four carbon compound? –It’s re-used to form another citric acid molecule. And so the cycle goes on and on.