Pyruvate Oxidation Krebs Cycle. STEP 2: PYRUVATE OXIDATION.
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Transcript of Pyruvate Oxidation Krebs Cycle. STEP 2: PYRUVATE OXIDATION.
Pyruvate Oxidation & Krebs Cycle
STEP 2: PYRUVATE OXIDATION
Recall…
Recall Step 1 - Glycolysis
• Happens in the cytoplasm• Does not require oxygen (anaerobic)• Inefficient (net 2 ATP produced)
Glycolysis Summary
What went in:
• 1 Glucose• 2ATP• 2 NAD+
• 4 ADP• 4 Pi
What was produced:• 2 pyruvate• 2 ADP• 2 NADH + H+
• 4 ATP
Step 2 – Pyruvate Oxidation
Overview
The two pyruvate molecules formed in glycolysis are transported through the two mitochondrial membranes into the matrix
Within the matrix, enzymes catalyze the following three changes
Happens twice for every glucose molecule
Three Steps of Pyruvate Oxidation
1. A carboxyl group is removed as CO2
2. The remaining two-carbon molecule is oxidized by NAD+. This is a redox reaction – pyruvate is oxidized, and NAD+ is reduced
3. Coenzyme A (CoA) is attached to the carbon compound, forming acetyl-CoA
2 pyruvate + 2 NAD+ + 2 CoA 2 acetyl-CoA + 2 NADH + 2 CO2
Overall
The two molecules of acetyl-CoA enter the Krebs cycle The two molecules of NADH proceed to step 4 to
participate in oxidative phosphorylation The two CO2 molecules diffuse out of the cell as waste The two H+ molecules remain dissolved in the matrix No ATP is directly produced in this step
STEP 3: KREBS CYCLE
Overview
• also called the Citric Acid Cycle• named after the Nobel Prize winner who
discovered it• Occurs in the mitochondrial matrix• 8 step process• Remember that the Krebs Cycle happens
TWICE for every one molecule of glucose.
Overall
The Krebs cycle will produce the following products for every glucose molecule broken down
• 6 NADH• 2 FADH2• 2 ATP• 4 CO2