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b Oxidation

b Oxidation. Energy from Fats. Overview. Just the first part is different!. Definition. b Oxidation – fatty acids are used to make Acyl-CoA molecules and broken down in mitochondria to make Acetyl-CoA molecules, which can enter the Krebs Cycle .

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b Oxidation

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  1. b Oxidation Energy from Fats

  2. Overview Just the first part is different!

  3. Definition • b Oxidation – fatty acids are used to make Acyl-CoA molecules and broken down in mitochondria to make Acetyl-CoA molecules, which can enter the Krebs Cycle. • Acyl-CoA – temporary compound formed when coenzyme attaches to fatty acid

  4. Step 1: Activation of Fatty Acids by Acetyl CoA Note: 2P from ATP are utilized in this process

  5. Step 2: AcylCoA Enters the Matrix

  6. Step 3: Oxidation of AcylCoA 1. FAD+ oxidizes the bond between C2 and C3 2. Adding water results in the addition of OH to C3 3. NAD+ oxidizes that OH to a carbonyl group 4. CoA cleaves the bond between C2 and C3

  7. Notes • C1 = alpha C (Ca) and C2 = beta C (Cb), hence the term beta oxidation • Products: • AcylCoA (which undergoes b oxidation again) • Acetyl CoA (which enters the Krebs cycle) • NADH and FADH2 (which are utilized by ETC)

  8. Example: Palmitate (16 C) ATP Yield Palmitoyl CoA + 7FAD + 7NAD + 7CoA + 7H2O 8Acetyl CoA + 7FADH2 + 7NADH + 7H+

  9. How much ATP did Palmitate yield? • 8 acetyl CoA enter citric acid cycle and give: • 24 NADH = 72 ATP (by oxidative phosphorylation) • 8 FADH2 = 16 ATP (by oxidative phosphorylation) • 8 GTP = 8 ATP • 7 NADH generated by beta oxidation itself = 21 ATP (by oxidative phosphorylation) • 7 FADH2 generated by beta oxidation itself = 14 ATP (by oxidative phosphorylation) • Total number of ATP from 1 molecule of palmitate = 72 + 16 + 8 + 21 + 14 = 131. • But REMEMBER: we used to high energy phosphate bonds (equivalent of 2 ATP) to activate palmitate to palmitoyl CoA. Therefore, the ATP yield is 129.

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