1. Pyruvate Oxidation

2. Mitochondria In eukaryotes, mitochondria produce the majority of the cell’s ATP Mitochondria: oval shaped organelles with a double membrane Inner membrane is folded; the folds are called cristae Many proteins and enzymes embedded to help cellular respiration

3. Mitochondria The matrix is the protein-rich fluid inside the cristae The fluid-filled space between the two membranes is the intermembrane space

4. Mitochondria Steps 2-4 of cellular respiration all occur in mitochondria Step 2: pyruvate oxidation Step 3: Krebs cycle Step 4: Electron transport chain Occurs in the inner membrane

5. Pyruvate Oxidation Two pyruvates formed from glycolysis are transported into the matrix

6. Pyruvate Oxidation 1.Carboxyl removed as CO 2 2.Pyruvate is oxidized into acetate 1.NAD+ is reduced to NADH 3.Coenzyme-A is added, forming Acetyl-coA

7. Pyruvate Oxidation Overall reaction: 2 pyruvate + 2NAD + + 2 CoA --> 2 acetyl-CoA + 2NADH + 2H + + 2CO 2 Acetyl-CoA is the central molecule in energy metabolism Most macromolecules are changed into acetyl-coA If you need energy, it is used to produce ATP If you don’t need energy, it is used to produce fat

8. Krebs cycle The acetyl-CoA from pyruvate oxidation enters Krebs cycle Remember, 2x acetyl-CoA are produced per glucose 8-step process Each step catalyzed by a specific enzyme The product of step 8 is the reactant in step 1

9. Krebs cycle By the end of the cycle: The original glucose molecule is consumed The 6 carbon atoms in glucose are released as CO 2 6 NADH (3 per acetyl-CoA) 2 FADH2 (1 per acetyl-CoA) 2 ATP (1 per acetyl-CoA)

10. What’s left of glucose? Through glycolysis, pyruvate oxidation and Krebs cycle, 1 molecule of glucose produced: 4 ATP (2 from glycolysis, 2 from Krebs cycle) 2 NADH (pyruvate oxidation) 6 NADH (Krebs cycle) 2 FADH 2 Most of the energy from glucose will be produced in the next stage (Electron Transport Chain)