Chapter 1: Introduction — DNA Repair is Integrated with Many Cellular Processes

Long-term survival of a species requires cellular mechanisms that efficiently safeguard DNA, the chemical material of the genome. All known living organisms have several mechanisms that repair different types of DNA damage. This is essential to prevent cytotoxic and mutagenic effects of damage to DNA. In fact, each cell in the body is inflicted by tens of thousands of DNA lesions per day from spontaneous chemical decay and normal cellular metabolites alone. Environmental chemicals, ultraviolet and ionizing radiation add to the burden of genome damage. Without cellular mechanisms that maintain DNA, we would probably die within a few days from multiple organ failure due to inactivation of numerous genes in each cell. Fortunately, a number of mechanisms contribute to maintaining DNA, including high fidelity DNA replication, DNA repair, cell cycle regulation, as well as removal of cells with serious genetic defects by apoptosis (programmed cell death) (Fig. 1.1). However, this is just the tip of the iceberg, as outlined below.