alculate the metabolic energy yield from oxidation of stearic acid, taking into account the energy needed to activate the fatty acid and transport it into mitochondria.(2 mark) (b) Do the same for oleic acid. (1 mark)

(a) Stearic acid is a saturated fatty acid with 18 carbons.

Step 1: Activation of stearic acid requires 2 ATPs.

Step 2: The fatty acid is transported into the mitochondria, which also requires energy but we'll assume it's negligible for this calculation.

Step 3: The stearic acid undergoes beta-oxidation. Each round of beta-oxidation yields 1 FADH2, 1 NADH, and 1 acetyl-CoA. Since stearic acid has 18 carbons, it will undergo 8 rounds of beta-oxidation, yielding 8 FADH2, 8 NADH, and 9 acetyl-CoA.

Step 4: Each FADH2 yields 1.5 ATPs and each NADH yields 2.5 ATPs in the electron transport chain. Each acetyl-CoA enters the citric acid cycle, yielding 3 NADH, 1 FADH2, and 1 GTP.

So, the total ATP yield from stearic acid is:

(8 FADH2 x 1.5 ATP/FADH2) + (8 NADH x 2.5 ATP/NADH) + (9 acetyl-CoA x [3 NADH x 2.5 ATP/NADH + 1 FADH2 x 1.5 ATP/FADH2 + 1 GTP]) - 2 ATP (for activation)

= 12 ATP (from FADH2) + 20 ATP (from NADH) + 9 x [7.5 ATP + 1.5 ATP + 1 ATP] - 2 ATP

= 12 ATP + 20 ATP + 9 x 10 ATP - 2 ATP

= 32 ATP + 90 ATP - 2 ATP

= 120 ATP

(b) Oleic acid is an unsaturated fatty acid with 18 carbons and one double bond.

The calculation is similar to stearic acid, but one round of beta-oxidation is replaced by an isomerization step, which does not yield any FADH2. So, the total ATP yield from oleic acid is:

(7 FADH2 x 1.5 ATP/FADH2) + (8 NADH x 2.5 ATP/NADH) + (9 acetyl-CoA x [3 NADH x 2.5 ATP/NADH + 1 FADH2 x 1.5 ATP/FADH2 + 1 GTP]) - 2 ATP

= 10.5 ATP (from FADH2) + 20 ATP (from NADH) + 9 x 10 ATP - 2 ATP

= 30.5 ATP + 90 ATP - 2 ATP

= 118.5 ATP

So, the metabolic energy yield from oxidation of stearic acid is 120 ATP and from oleic acid is 118.5 ATP.

(a) Stearic acid is a saturated fatty acid with 18 carbons.

Step 1: Activation of stearic acid requires 2 ATPs.

Step 2: The beta-oxidation of stearic acid. Since stearic acid has 18 carbons, it will undergo 8 rounds of beta-oxidation, producing 9 Acetyl-CoA, 8 FADH2, and 8 NADH.

Step 3: The energy yield from the oxidation of Acetyl-CoA in the citric acid cycle. Each Acetyl-CoA produces 3 NADH, 1 FADH2, and 1 GTP. So, 9 Acetyl-CoA will produce 27 NADH, 9 FADH2, and 9 GTP.

Step 4: Calculate the total ATP yield. Each NADH produces 2.5 ATP, each FADH2 produces 1.5 ATP, and each GTP produces 1 ATP. So, the total ATP yield is (2.535) + (1.517) + 9 - 2 (used for activation) = 87.5 + 25.5 + 9 - 2 = 120 ATP.

(b) Oleic acid is a monounsaturated fatty acid with 18 carbons and one double bond.

Step 1: Activation of oleic acid requires 2 ATPs.

Step 2: The beta-oxidation of oleic acid. Since oleic acid has 18 carbons, it will undergo 8 rounds of beta-oxidation, producing 9 Acetyl-CoA, 7 FADH2, and 8 NADH. The double bond in oleic acid results in one less FADH2.

Step 3: The energy yield from the oxidation of Acetyl-CoA in the citric acid cycle. Each Acetyl-CoA produces 3 NADH, 1 FADH2, and 1 GTP. So, 9 Acetyl-CoA will produce 27 NADH, 9 FADH2, and 9 GTP.

Step 4: Calculate the total ATP yield. Each NADH produces 2.5 ATP, each FADH2 produces 1.5 ATP, and each GTP produces 1 ATP. So, the total ATP yield is (2.535) + (1.516) + 9 - 2 (used for activation) = 87.5 + 24 + 9 - 2 = 118.5 ATP.