In humans, damage to DNA has been implicated in many cancers as well as in certain aspects of aging. Genetic diseases such as cystic fibrosis and sickle cell disease can be caused by a single DNA mutation in one gene.
Types of Dna Damage
Damage to DNA can result from several different types of processes. Hydrolysis, deamination, alkylation, and oxidation are all capable of causing a modification in one or more bases in a DNA sequence.
Hydrolysis.
DNA consists of long strands of sugar molecules called deoxyribose that are linked together by phosphate groups. Each sugar molecule carries one of the four natural DNA bases: adenine, guanine, cytosine, or thymine (A, G, C, or T). The chemical bond between a DNA base and its respective deoxyribose, although relatively stable, is nonetheless subject to chance cleavage by a water molecule in a process known as spontaneous hydrolysis. Loss of the "purine" bases (guanine and adenine) is referred to as depurination, whereas loss of the "pyrimidine" bases (cytosine and thymine) is called depyrimidination. In mammalian cells, it is estimated that depurination occurs at the rate of about 10,000 purine bases lost per cell generation. The rate of depyrimidination is considerably slower, resulting in the loss of about 500 pyrimidine bases per cell generation.
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