Welcome to My AP Biology Thoughts podcast, my name is Pauline Brillouet and I am your host for episode #73 called Unit 3 Cellular Energetics: Pyruvate Oxidation. Today we will be discussing the details and significance of this step of cellular respiration.

•  Pyruvate oxidation is the second step in cellular respiration. It is often called the link reaction because it bridges glycolysis to the krebs cycle. The process takes place in the mitochondrial matrix of eukaryotes. The reactants are pyruvate and CoA, and the products are carbon dioxide and acetate. It’s whole purpose is to further oxidize the original glucose molecule that how now split into two pyruvate molecules

•  Pyruvate is a 3 carbon sugar left over from glycolysis. A carboxyl group is removed from pyruvate, releasing carbon dioxide and leaving it as a 2 carbon sugar. Pyruvate was therefore essentially oxidized and lost electrons. These lost electrons are then used to reduce NAD+ to NADH, so NAD+ is gaining an electron. The 2 carbon sugar now called acetate then binds to coenzyme A (CoA) to form acetyl CoA.

•  The process of pyruvate oxidation is essential because of its products. The carbon dioxide that is released is then able to be ingested by plants so that they can perform photosynthesis. The acetyl CoA produced is needed to kick start the next step in cellular respiration called the krebs cycle. Finally, the reduction of NAD+ to NADH is very important because NADH is now an electron carrier that will get oxidized later in the electron transport system. The oxidation of NADH allows for a proton gradient across the inner mitochondrial membrane to diffuse back through the ATP synthase. This process is also helpful to help visualize redox reactions, where reduction must happen with oxidation and vice versa. NAD+ is only able to be reduced because the pyruvate was oxidized. Overall, glucose is simply being further oxidized in this link reaction to ultimately produce ATP for cell work and functioning. 
• Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. 

Music Credits:

• "Ice Flow" Kevin MacLeod (incompetech.com)
• Licensed under Creative Commons: By Attribution 4.0 License
• http://creativecommons.org/licenses/by/4.0/

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