Final answer:
Carbohydrates, fats, and proteins are metabolized to produce energy in the form of ATP. Fats provide the largest amount of free energy.
Step-by-step explanation:
The metabolism of carbohydrates, fats, and proteins releases energy in the form of Adenosine Triphosphate (ATP).
In the case of carbohydrates, the process begins with glycolysis, where glucose is broken down into smaller sugars, producing ATP and NADH. Under aerobic conditions, pyruvate enters the Krebs cycle, generating more ATP, FADH2, and NADH. These high-energy molecules are used in oxidative phosphorylation to produce even more ATP.
Fats are converted into fatty acids and glycerol through lipolysis. The fatty acids go through beta-oxidation to produce acetyl-CoA, which enters the Krebs cycle to generate ATP, FADH2, and NADH.
Proteins are broken down into amino acids through proteolysis. Certain amino acids can enter the Krebs cycle directly to produce ATP, while others are converted into molecules that can enter the Krebs cycle.
Of these molecules, fats provide the largest amount of free energy because they have the highest energy content per gram compared to carbohydrates and proteins.