Final answer:
The energy from macronutrients is transferred to ATP via oxidative phosphorylation, which includes the Krebs cycle and the electron transport chain, with ATP synthase producing ATP through chemiosmosis.
Step-by-step explanation:
The mechanism by which the energy produced from carbohydrates, proteins, and lipids is transferred to adenosine triphosphate (ATP) is through a process called oxidative phosphorylation. This complex process involves two main parts: the Krebs cycle (also known as the citric acid cycle) and the electron transport chain (ETC). During the Krebs cycle, which occurs in the mitochondria, energy-containing molecules like NADH and FADH2 are produced. These molecules carry electrons to the ETC, where their energy is used to pump protons across the mitochondrial membrane, creating a gradient. ATP is then produced as protons flow back through the enzyme ATP synthase, a process called chemiosmosis.
Glycolysis and beta-oxidation are relevant as well, with glycolysis breaking down glucose into pyruvate, which then enters the Krebs cycle, and beta-oxidation breaking down fatty acids to produce acetyl-CoA, also entering the Krebs cycle.