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Radiolysis of intracellular water by ionizing radiation creates peroxides, which are relatively stable precursors to hydroxyl radicals. 60%–70% of cellular DNA damage is caused by hydroxyl radicals, [3] yet hydroxyl radicals are so reactive that they can only diffuse one or two molecular diameters before reacting with cellular components.
DNA may be modified, either naturally or artificially, by a number of physical, chemical and biological agents, resulting in mutations. Hermann Muller found that "high temperatures" have the ability to mutate genes in the early 1920s, [2] and in 1927, demonstrated a causal link to mutation upon experimenting with an x-ray machine, noting phylogenetic changes when irradiating fruit flies with ...
Types of mutations that can be introduced by random, site-directed, combinatorial, or insertional mutagenesis. In molecular biology, mutagenesis is an important laboratory technique whereby DNA mutations are deliberately engineered to produce libraries of mutant genes, proteins, strains of bacteria, or other genetically modified organisms. The ...
It develops because radiation causes DNA mutations directly and indirectly. Direct effects are those caused by ionizing particles and rays themselves, while the indirect effects are those that are caused by free radicals, generated especially in water radiolysis and oxygen radiolysis.
The ability for the wrong tautomer of one of the standard nucleic bases to mispair causes a mutation during the process of DNA replication which can be cytotoxic or mutagenic to the cell. These mispairings can result in transition , transversion , frameshift , deletion , and/or duplication mutations. [ 18 ]
They can affect the transcription and replication of the DNA, which in severe cases can lead to cell death. The mutagen produces mutations in the DNA, and deleterious mutation can result in aberrant, impaired or loss of function for a particular gene, and accumulation of mutations may lead to cancer. Mutagens may therefore be also carcinogens.
In humans, RAD51 is a 339-amino acid protein that plays a major role in homologous recombination of DNA during double strand break repair.In this repair process, an ATP-dependent DNA strand exchange takes place in which a template strand invades base-paired strands of homologous DNA molecules.
Suppressor mutations can be described as second mutations at a site on the chromosome distinct from the mutation under study, which suppress the phenotype of the original mutation. [14] If the mutation is in the same gene as the original mutation it is known as intragenic suppression , whereas a mutation located in a different gene is known as ...