Role of free radicals in cell injury OR mechanism of cell injury by free radicals.

The effects of reactive oxygen species are wide ranging, but three reactions are particularly relevant to cell injury:

1. Lipid peroxidation of membrane: Free radicals in the presence of oxygen may cause peroxidation of lipids within plasma and organellar membrane
2. Oxidative Modification of protein: Oxidative modification enhances degradation of critical proteins by the multicatalytic proteosome complex, raising havoc throughout cell.
3. Lesions in DNA: Reactions with thymine in nuclear and mitochondrial DNA produce single stranded breaks in DNA.