DNA damage

DNA damage is an alteration of DNA’s chemical structure or sequence caused by physical, chemical, or biological agents. It can disrupt replication or gene expression and may be repaired, persist, or become a mutation.

Base excision repair: A pathway that removes damaged or inappropriate DNA bases and restores the affected strand. It repairs small chemical lesions such as oxidized or deaminated bases.
DNA: The hereditary molecule that stores genetic information in the sequence of its nucleotide bases. Damage alters the chemical structure or sequence of this molecule.
Mutagenesis: The process by which genetic mutations arise, spontaneously or through exposure to mutagens. Unrepaired or incorrectly repaired damage can become a mutation.
Ultraviolet radiation: Electromagnetic radiation with wavelengths shorter than visible light and longer than X-rays. It can create covalent links between neighboring DNA bases.
Mutation: A heritable change in the nucleotide sequence of DNA. A lesion can become a mutation when copied or repaired inaccurately.
Nucleotide excision repair: A pathway that removes short DNA segments containing bulky lesions, then fills the resulting gap. It removes helix-distorting damage, including ultraviolet-induced photoproducts.
Nucleotide: A molecular unit made of a nitrogenous base, a sugar, and one or more phosphate groups. Lesions can modify nucleotide bases, sugars, or the bonds linking them.
Carcinogenesis: The multistep process by which normal cells acquire changes that lead to cancer. Accumulated DNA damage can initiate or accelerate cancer-driving mutations.
Ionizing radiation: Radiation energetic enough to remove electrons from atoms or molecules. It causes DNA breaks and chemical lesions directly or through reactive species.
Apoptosis: A regulated form of cell death that removes cells through an organized molecular program. Severe or irreparable damage can trigger this protective response.

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