DNA damage

DNA damage refers to physical or chemical contamination in the environment that causes changes in the cellular DNA structure of the body. There are many kinds of chemical substances causing DNA damage. For example, nitrosamines are first metabolized and decomposed in the body to produce an alkylating agent, diazonium, which causes alkylation of DNA and causes irreparable changes in genetic information carriers. Carcinogenic. Another example is benzo(a)pyrene in polycyclic aromatic hydrocarbons (PAH), which, under the activation of mixed functional oxidases, forms an epoxide with an electrophilic structure. This epoxide combines with a nucleophilic group of a macromolecule such as intracellular DNA to cause DNA damage. When the damage cannot be repaired or repaired, it is possible to cause the cells to become cancerous. Some metals, such as nickel, strontium, chromium and other carcinogens, may also form a stable complex with ribonucleic acid residues, resulting in carcinogenic effects. [DNA damage repair] DNA damage repair refers to the recovery of the structure of DNA molecules in biological cells after damage, and is the result of the action of various enzymes in the body cells. In 1968, American scholar J. E. Clifford first discovered that autosomal recessive photochemical cancerous disease in humans is caused by a defect in the repairing kinetic energy of DNA damage caused by genetic mutation. This finding provides an important molecular biological evidence for the pathogenesis of malignant tumors, and has also led to the study of DNA damage repair in the medical field. DNA damage repair was listed as one of the important topics at the 14th International Conference on Genetics held in Moscow in 1979. Research on DNA damage repair has become an important research topic in genetics and oncology in molecular and genetic medicine. There are many types of ADN molecular damage. For example, the formation of thymine dimer is the main damage mode of UV to DNA molecules. After x-ray and r-ray irradiation, the hydrogen bond between DNA strands can be broken. Single-strand or double-strand breaks; mitomycin C can cause cross-linking between single strands of DNA molecules, and cross-linking of strands can cause cleavage of DNA molecules; DNA molecules can also undergo changes in individual bases or nucleotides. The methods of DNA damage repair include photoreactivation, cut repair, post-replication repair, adaptive repair, chain break repair, and chain cross-link repair. DNA damage repair studies can help to understand the mechanism of gene mutation, aging and cancer, and can also be applied to the detection of environmental carcinogens.