Final answer:
Superoxide anions and peroxides are endogenous agents that cause oxidative damage to the primary structure of DNA. The body uses antioxidants and enzymes to defend against such damage. Exogenous sources of DNA damage include environmental factors like UV light and industrial chemicals.
Step-by-step explanation:
Superoxide anions (O2·-) and peroxides arise from endogenous sources of DNA damage. These reactive oxygen species (ROS), such as peroxides and free radicals, are highly reactive products of normal cellular processes, including mitochondrial ATP production and oxygen metabolism. ROS can cause oxidative damage to DNA, potentially leading to mutations and contributing to aging and diseases like cancer.
The body has defense mechanisms, like antioxidants and enzymes, to prevent and repair oxidative damage. Endogenous agents like ROS can modify the primary structure of the DNA double helix, introducing chemical modifications and disrupting the helix's regular structure, hence affecting its integrity and function.
Exogenous agents, in contrast, include environmental factors like UV light and industrial chemicals, which also can cause damage to DNA, but through external means. For example, UV-B light can lead to direct DNA damage by creating pyrimidine dimers between adjacent cytosine and thymine bases.