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A somatic mutation is a change in the DNA sequence of a ... and somatic tissues likely reflects the ... repair of such damage that occurs all ...
In eukaryotes, ATP-dependent chromatin remodeling complexes and histone-modifying enzymes are two factors that act to accomplish this remodeling process after DNA damage occurs. [60] Further DNA repair steps, involving multiple enzymes, usually follow. Some of the first responses to DNA damage, with their timing, are described below.
Mutation and DNA damage are the two major types of errors that occur in DNA, but they are fundamentally different. DNA damage is a physical alteration in the DNA structure, such as a single or double strand break, a modified guanosine residue in DNA such as 8-hydroxydeoxyguanosine, or a polycyclic aromatic hydrocarbon adduct. DNA damages can be ...
As well as mutations to DNA damage repair genes, mutations also arise in the genes responsible for arresting the cell cycle to allow sufficient time for DNA repair to occur, and some genes are involved in both DNA damage repair and cell cycle checkpoint control, for example ATM and checkpoint kinase 2 (CHEK2) – a tumor suppressor that is ...
The likely major underlying cause of mutations in cancer is DNA damage. [citation needed] For example, in the case of lung cancer, DNA damage is caused by agents in exogenous genotoxic tobacco smoke (e.g. acrolein, formaldehyde, acrylonitrile, 1,3-butadiene, acetaldehyde, ethylene oxide and isoprene). [25]
[7] [8] When these imaginal discs are exposed to genotoxic substances genetic mutations occur due to possible DNA damage that can be inherited by the progeny cells during mitosis. The phenotypic forms of these genetic mutations can be observed in adult body forms, like the wings and the eyes, and thus can be examined using the wing-spot test ...
A germline mutation can also occur due to exogenous factors. Similar to somatic mutations, germline mutations can be caused by exposure to harmful substances, which damage the DNA of germ cells. This damage can then either be repaired perfectly, and no mutations will be present, or repaired imperfectly, resulting in a variety of mutations. [11]
The somatic mutations and epigenetic alterations caused by DNA damage and deficiencies in DNA repair accumulate in field defects. Field defects are normal-appearing tissues with multiple alterations (discussed in the section below), and are common precursors to development of the disordered and over-proliferating clone of tissue in a cancer.