Question

Maximum amount of energy/ATP is liberated on oxidation of:

• A. fats
• B. proteins
• C. starch
• D. vitamins

Answer 1

Answer: (A)

Fat is a triglyceride made of a molecule of glycerol and three molecules of fatty acid. Glycerol forms glyceraldehyde phosphate which yields $18-19$ ATP molecules. Fatty acid undergo $\beta$ - oxidation and forms acetyl $Co-A,NAD{H}_2$ and $FAD{H}_2$. Acetyl Co-A enters Krebs cycle and yields $12$ ATP. Therefore, fats provides more energy per gram as compared to carbohydrate. For example Palmitic acid $\left(C_6{H}_{32}{O}_2\right)$ yields 8 acetyl Co-A and $7\left(NAD{H}_2+FAD{H}_2\right)$ i.e., $129$ ATP.