DNA repair

The DNA repair refers to a collection of processes through that a cell recognized and corrects damage to the DNA molecules which encode its genome. The human cells both normal metabolic activities and environmental factors like as radiation and UV light can cause DNA damage resulting in as several as 1 million individual molecular lesions per cell per day. Several of these lesions cause structural damage to the DNA molecule and can alter or eliminate the cell's ability to transcribe the gene in which the affected DNA encodes. Another lesion induces potentially harmful mutations in the cell's genome that affect the survival of its daughter cells after it undergoes mitosis. As a consequence the DNA repair procedure is constantly active as it responds to damage in the DNA structure. While normal repair processes fail and when cellular apoptosis does not occur irreparable DNA damage may occur including double-strand breaks and DNA crosslinkages.

DNA repair ability of a cell is vital to the integrity of its genome and therefore to its normal functioning and in which of the organism. Several genes which were initially described to influence life span have turned out to be involved in DNA damage protection and repair. Failure to correct molecular lesions in cells which form gametes can introduce mutations into the genomes of the offspring and therefore influence the rate of evolution.