(i) Anaerobic catabolism of starch with 300 glucose units
(ii) Aerobic catabolism of glucose
(iii) Aerobic catabolism of acetate
(iv) Aerobic catabolism of palmitate
Metabolic ATP Generation Comparison
This solution determines the increasing order of ATP generated from the metabolism of different compounds under specified conditions. We analyze the approximate ATP yield for each case:
1. Anaerobic Catabolism of Starch (300 Glucose Units)
- Starch is a polysaccharide composed of glucose units.
- Anaerobic metabolism (fermentation) of one glucose molecule yields a net of 2 ATP molecules via glycolysis.
- For 300 glucose units, the total ATP generated is approximately:
$ 300 \text{ units} \times 2 \text{ ATP/unit} = 600 \text{ ATP} $
- Designation: (i)
2. Aerobic Catabolism of Glucose
- Complete aerobic respiration of one glucose molecule involves glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation.
- This process yields approximately 30 to 32 ATP molecules per molecule of glucose. Let's use ~30 ATP for comparison.
- Designation: (ii)
3. Aerobic Catabolism of Acetate
- Acetate is typically metabolized via conversion to acetyl-CoA.
- One molecule of acetyl-CoA entering the citric acid cycle generates approximately 10 ATP molecules (from NADH, FADH2, and GTP).
- Designation: (iii)
4. Aerobic Catabolism of Palmitate
- Palmitate is a 16-carbon fatty acid ($C_{16}H_{32}O_2$).
- Its complete aerobic metabolism involves beta-oxidation followed by the citric acid cycle.
- Beta-oxidation of palmitate produces 8 acetyl-CoA molecules, 7 NADH, and 7 FADH2. Activation requires 2 ATP equivalents.
- Estimated ATP yield:
$ (8 \times 10 \text{ ATP from acetyl-CoA}) + (7 \times 2.5 \text{ ATP from NADH}) + (7 \times 1.5 \text{ ATP from FADH}_2) - 2 \text{ ATP (activation)} $
$ = 80 + 17.5 + 10.5 - 2 = 106 \text{ ATP} $
- Designation: (iv)
Determining the Increasing Order
Comparing the approximate ATP yields:
- (iii) Acetate: ~10 ATP
- (ii) Glucose: ~30 ATP
- (iv) Palmitate: ~106 ATP
- (i) Starch (300 units): ~600 ATP
Arranging these in increasing order of ATP generated:
(iii) < (ii) < (iv) < (i)
Therefore, the correct sequence is (iii), (ii), (iv), (i).
Important Questions from Bioenergetics ATP Hydrolysis
- Assuming that there are $5 \times 10^{13}$ cells in the human body, and that ATP is turning over at a rate of $10^9$ ATP molecules per minute in each cell, then the human body is utilizing ________ watts (rounded off to two decimal places).
[Assume that hydrolysis of ATP yields 12 kcal per mole. 1 watt = 1 joule/sec, 1 calorie = 4.18 joules, Avogadro's number = $6.023 \times 10^{23}$] - Glucose and hexanoic acid, each having six carbon atoms can undergo complete biological oxidation. In terms of net ATP generation, which of the following statements is CORRECT?
- Four groups of metabolites are given below. Choose the group in which all the compounds contain at least one bond whose ${\Delta}G'^{\circ}$ of hydrolysis is $\leq$ -7.0 kcal/mole.
- Which one of the following statements is NOT correct?
- Which of the following is TRUE about Kreb's cycle?
