ABSTRACT
The oxidative phosphorylation is the principal source of ATP of aerobic organisms. The oxidative phosphorylation is carried out in respiratory assemblies located in the internal membrane of the mitochondrion, whereas the citric acid cycle and the oxidization pathway of fatty acids which bring the most part of NADH and FADH2, also treated in the course of the oxidative phosphorylation, are located in the adjacent matrice of the mitochondrion. The thermodynamic cause (origin) of the occurrence of the oxidative phosphorylation is the decline in the Gibbs energy accompanying the whole process. Photosynthesis in green plants occurs in membranes called thylakoid membranes that lie inside chloroplasts. As mitochondria, chloroplasts possess inner and outer membranes. In photosynthesis, the energy of light is trapped by chlorophyll and is used to generate a proton gradient. During darkness, the carbohydrates, proteins and lipids, which after photosynthesis contain the energy originally derived from sunlight, can then be utilized as foods by cells of the ‘‘animal world”.
