Kreb’s Cycle and ETC

Oxygen is Present If oxygen is present at the end of glycolysis, pyruvic acid enters the aerobic pathway. The acid changes to become Acetyl-CoA. Here it will enter the Krebs Cycle (Citric Acid Cycle) During the Krebs Cycle, Acetyl-CoA undergoes a series of reactions that further break it down and make energy ( 2 ATP)

Krebs Cycle Pyruvic Acid undergoes a few reactions before it enters the Krebs cycle. It becomes a molecule called Acetyl-CoA Acetyl-CoA enters the cycle This takes place in the mitochondria

Krebs Cycle (Cont.) Acetyl-CoA is broken down into ATP and Carbon Dioxide. Each Acetyl-CoA molecule goes through the cycle twice in order to make two ATP molecules. Carbon Dioxide is given off as waste

Electron Transport Chain Further inside the mitochondria, the last stage of respiration takes place. Here the cell makes 32 ATP!!! Energized electrons get passed down a chain of proteins. They give off energy at each protein(ATP)

ETC (Cont.) The last stop in the chain is an oxygen molecule. The cycle stops when oxygen combines with 2 hydrogen to make the last waste product…. WATER!!!

Summary During Respiration we make : 1. Glycolysis – 4 ATP 2. Krebs Cycle - 2 ATP 3. Electron Transport Chain - 32 ATP 4. Total- 38 ATP!

Glucose Glycolysis Yes Oxygen No Oxygen Yeast Human ____ ATP ____ as waste Kreb’s Cycle ____ ATP ____ Final Electron Acceptor Fermentation Electron Transport Chain