Chemical damage to DNA bases
In addition, it is the secret of life, the DNA molecule, chemical substances as well as other molecules of heterocyclic bases of DNA phosphate salt, and sugar, is a reagent containing ultraviolet or ionizing radiation, carcinogens sensitive to change, it is a chemical substance. Important examples of some of the changes can occur in the DNA bases, deaminated oxidation of 8-position of guanine and adenine hydroxyl radicals and oxidant methylated cytosine, guanine alkylnitrosoureas, produced by γ rays I include.
It is included in the development of cancer induction and cell damage DNA. DNA of human cells were subjected to one million thousands of adverse events for each day that is generated by the (endogenous) process internal and metabolism (exogenous) outside of both. Change in cell genome can be used to generate an error translated subsequent protein necessary for cell function and signaling and transcription of DNA. If it is not fixed in mitosis before genomic mutation, can be transmitted to the generation of daughter cell mutation. After losing the ability to repair the DNA the cells were damaged effectively, there is a possible three answers. Or years, exogenous source of injury was considered a major cause of DNA mutations leading to cancer. However, lobe Jackson and contributes significantly to mutations to produce a cell source and two malignancy.5 environmental causes DNA damage endogenous, but suggested that it may lead to similar types of DNA damage.
DNA can be used to attack by chemical mutagens and physical. Physical mutation is a radiation source comprising a radiation from the sun (wavelength 200-300 nm) UV preferably. Ultraviolet light to generate the covalent attachment of a base (cytosine and thymine) DNA intrastrand cross-linking adjacent pyrimidine. By generating free radicals in the production cells reactive oxygen species (ROS), start the DNA mutation, ionizing radiation (X-ray) leads to a double-strand break in the double helix and one strand. Nitrogen mustard may be able to attach covalently bonded alkyl group to the DNA bases, ethylate or methyl DNA-based, chemical mutagens is an example of a DNA alkylating agent. The front carcinogen precursors chemically inert to be converted to the high reactivity of carcinogenic metabolically. Specifically, this chemical is associated with the carcinogens DNA which can react with DNA through the formation of DNA adducts. There is no carcinogenic benzo [a] pyrene, polycyclic heterocyclic ring. It undergoes oxidation continuous mediated by cytochrome P450 enzymes to provide pyrenediol epoxide (BPDE), carcinogenic metabolites can form a covalent DNA adducts of benzo.
Further DNA damage, it can be obtained from the biochemical reactions of some of them have no understood.6 hydrolysis reaction well nucleotide bases of DNA strands to be cut completely or partially and endogenous metabolism. Chemical bonds connecting the (guanine or adenine) purine base to deoxyribosyl phosphorus chain, will be able to break into a process called depurination spontaneously. 000 depurination event occurs occurs 10 per day in the (cytosine or loss pyrimidine base thymine) cell.7 Depyrimidination mammals, but at a rate of low 20 to 100 times higher than depurination. Respectively, as a result of uracil hypoxanthine, and xanthine, deamination occurs within the cell loss of the amino group of adenine, guanine, cytosine, ring. You can recognize enzymes, DNA repair, an unnatural base of these, be modified. However, the uracil base before the correction, which could be misinterpreted as a point mutation of C → T, which is then generated and thymine of DNA replication at the time.
DNA methylation of alkylation, a particular form occurs in cells by reactive S-adenosylmethionine and (SAM). SAM is a metabolic intermediate in cells containing a methyl group of highly reactive. In mammalian cells, 5 ‘guanosine nucleotide (G), i.e., methylation of the 5 (C) ring cytosine bases cytidine in CpG sequences – is performed at the position. 5 of methyl ATION an important source of error, – methyl cytosine, is a deamination of spontaneous mutation of the product. Loss of the amino groups results thymine base undetected enzymes, DNA, in a non-natural bases. Rotation obtained is retained to create a point mutation C → T on the replication of DNA.
Ormal metabolic processes that generate (ROS) change reactive oxygen species from oxidation bases. You are eligible purine and pyrimidine bases, oxidation. As a consequence of – (oxo-DG 8), 8 – oxo-deoxyguanosine join – and oxidized to dihydroguanine – -7,8 oxo-8 mutant guanine nucleotide most frequently. Oxo-DG can be based on the pairing pairing deoxycytotidine with deoxyadenosine instead – 8 as expected. If this error is detected, it is not corrected by the mismatch repair enzymes are DNA replication followed but includes a C → point mutations. The ROS, can cause double-strand breaks or single-stranded depurination, and depyrimidination to DNA. Genomic other mutations may be introduced during the DNA replication in S phase of the cell cycle. It may include nucleotides incorrectly based on the click-to – Duplicate polymerase smaller the DNA matrix, but has a significant error rate, Watson and template DNA.
Is not a nucleotide precursor which is chemically modified, it may be included in the DNA polymerase of the generated base normal. In addition, there is a tendency that the number of nucleotides that are repeated often, to “stuttering” in the part of the copy of DNA or containing the (microsatellite region) repeat sequence polymerase. This enzyme, “stuttering” due to the sliding direction, which is outside of the proper alignment with the template strand repeat of DNA. As a result, it is impossible to enter leading to the nucleotide daughter circuit too little or too much polymerase, the exact number of nucleotides indicated in the template DNA.
There is a possibility that the chain scission of double-stranded DNA and single occurs. The single-strand breaks, can cause damage to the deoxyribose of deoxyribosylphosphate of DNA strand. After the interrupt has removed the deoxyribose phosphate of AP-endonuclease 1.8 1 strand breaks to occur backbone of deoxyribose and nucleotide bases, as if they were lost from the structure of DNA, as an intermediate step of the base excision repair pathway cause. often, so that you can while rewinding in order to use as a template for replication, DNA is prone to damage, double-strand breaks can occur when cells pass through the S phase.