Question

1. Biological compounds such as carbohydrates, fats, and proteins are thermodynamically unstable in the presence of O₂, since, upon combustion, they will undergo exothermic reactions with O₂ to form CO₂, H₂O and other simple and stable compounds. But, such reactions do not occur naturally (our bodies do not spontaneously combust in air). On the other hand, aerobic life forms require O₂ for generating energy, via oxidation reactions (respiration), needed for myriad metabolic activities. Explain how the special electronic structure of O₂ allowed aerobic life on the planet to evolve in the presence of an oxidizing atmosphere. In addition, explain how these life forms are able to harvest energy from oxidation reactions under controlled conditions within cells. Hint: Most aerobic organisms have enzymes containing transition metal elements; these enzymes mediate and control the rates of the respiration or oxidation processes inside biological systems.

Answer 1