Arachidic acid is a C₂₀ fatty acid found in peanut and fish oils.
c. Calculate the total ATP yield from the complete β oxidation of arachidic acid by completing the following:

Verified step by step guidance

1. Step 1: Understand the structure of arachidic acid. Arachidic acid is a saturated fatty acid with the molecular formula C₂₀H₄₀O₂. This means it has 20 carbon atoms in its chain, and no double bonds.
2. Step 2: Determine the number of β-oxidation cycles. Each β-oxidation cycle shortens the fatty acid chain by 2 carbons, producing 1 acetyl-CoA molecule. For a 20-carbon fatty acid, the number of β-oxidation cycles is (20/2) - 1 = 9 cycles.
3. Step 3: Calculate the ATP yield from β-oxidation. Each β-oxidation cycle produces 1 FADH₂ and 1 NADH. Using the ATP equivalents (1 FADH₂ = 1.5 ATP, 1 NADH = 2.5 ATP), calculate the ATP yield from the 9 cycles: (9 × 1.5 ATP) + (9 × 2.5 ATP).
4. Step 4: Calculate the ATP yield from acetyl-CoA. Each acetyl-CoA enters the citric acid cycle, producing 3 NADH, 1 FADH₂, and 1 GTP (equivalent to 1 ATP). For 10 acetyl-CoA molecules (from 20 carbons), calculate the total ATP yield: (10 × 3 × 2.5 ATP) + (10 × 1 × 1.5 ATP) + (10 × 1 ATP).
5. Step 5: Subtract the ATP cost for activation. The activation of the fatty acid to form fatty acyl-CoA requires 2 ATP. Subtract this value from the total ATP yield calculated in the previous steps to determine the net ATP yield.

Key Concepts

Beta-Oxidation

Beta-oxidation is the metabolic process by which fatty acids are broken down in the mitochondria to generate acetyl-CoA, NADH, and FADH2. Each cycle of beta-oxidation shortens the fatty acid chain by two carbon atoms, producing energy carriers that enter the citric acid cycle for ATP production. Understanding this process is crucial for calculating the total ATP yield from fatty acids like arachidic acid.

ATP Yield Calculation

The ATP yield from fatty acid oxidation is calculated by considering the number of acetyl-CoA molecules produced and the energy carriers generated. Each acetyl-CoA can produce 10 ATP through the citric acid cycle, while NADH and FADH2 contribute additional ATP through oxidative phosphorylation. Knowing how to convert these energy carriers into ATP is essential for determining the total yield from arachidic acid.

Fatty Acid Structure

Arachidic acid, a saturated fatty acid with 20 carbon atoms, has a specific structure that influences its metabolic breakdown. The length and saturation of the fatty acid chain affect the number of beta-oxidation cycles required and the total ATP yield. Understanding the structural characteristics of fatty acids is important for predicting their behavior during metabolism.