Balancing the generation and elimination of reactive oxygen species.

The article provides information about the different aspects of the atmospheric gas Oxygen. Recent geochemical models oxygenation of suggest that Earth's atmosphere resulted in the emergence of aerobic organisms followed by a great diversification of biological species and the eventual evolution of humans. Although oxygen is thought to have been responsible for the expansion of life on Earth, there are two sides to this molecule: life giving and life taking. Oxygen in the air that one breathes is a relatively non-reactive chemical. However, when oxygen is exposed to high-energy or electron transferring chemical reactions, it can be converted to various highly reactive chemical forms collectively designated reactive oxygen species, which are toxic to biological organisms because they oxidize lipids, proteins, DNA, and carbohydrates, resulting in the breakdown of normal cellular, membrane, and reproductive functions.