Final answer:
The mechanisms of side-chain oxidation involve initiation, propagation, and termination steps in radical reactions, with biological implications such as the oxidation of fatty acids and contributions to cardiovascular diseases. Organisms defend against such reactions using radical scavengers like vitamin E.
Step-by-step explanation:
The question pertains to the mechanisms of side-chain oxidation by radicals, particularly in biological contexts such as the oxidation of fatty acids. Through the initiation, propagation, and termination phases of free radical reactions, fatty acids undergo side-chain oxidation, leading to the creation of hydroperoxides. These hydroperoxides are unstable and their decomposition results in short-chain aldehydes and carboxylic acids, causing the rancid smell of aged fats. A similar process occurs with low-density lipoproteins in arteries, contributing to cardiovascular diseases.
Biological systems also have defense mechanisms against such radical damage. For example, vitamin E acts as a radical scavenger in fats, disrupting the chain reactions of free radicals thereby preventing further damage. Free radical reactions are a significant aspect of biochemistry, important in processes like aging, food preservation, and various industrial applications.