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Synonymous mutations occur due to the degenerate nature of the genetic code. If this mutation does not result in any phenotypic effects, then it is called silent, but not all synonymous substitutions are silent. (There can also be silent mutations in nucleotides outside of the coding regions, such as the introns, because the exact nucleotide ...
However, the mutation rate does vary over the genome. [4] When the mutation rate in humans increases certain health risks can occur, for example, cancer and other hereditary diseases. Having knowledge of mutation rates is vital to understanding the future of cancers and many hereditary diseases. [5]
Germline mutations can occur before fertilization and during various stages of zygote development. [3] When the mutation arises will determine the effect it has on offspring. If the mutation arises in either the sperm or the oocyte before development, then the mutation will be present in every cell in the individual's body. [4]
When mutations occur, they may alter the product of a gene, or prevent the gene from functioning, or have no effect. About half of the mutations in the coding regions of protein-coding genes are deleterious — the other half are neutral. A small percentage of the total mutations in this region confer a fitness benefit. [31]
Point mutations may arise from spontaneous mutations that occur during DNA replication. The rate of mutation may be increased by mutagens. Mutagens can be physical, such as radiation from UV rays, X-rays or extreme heat, or chemical (molecules that misplace base pairs or disrupt the helical shape of DNA). Mutagens associated with cancers are ...
Frameshift mutations are known to be a factor in colorectal cancer as well as other cancers with microsatellite instability. As stated previously, frameshift mutations are more likely to occur in a region of repeat sequence. When DNA mismatch repair does not fix the addition or deletion of bases, these mutations are more likely to be pathogenic.
In genetics, a deletion (also called gene deletion, deficiency, or deletion mutation) (sign: Δ) is a mutation (a genetic aberration) in which a part of a chromosome or a sequence of DNA is left out during DNA replication. Any number of nucleotides can be deleted, from a single base to an entire piece of chromosome. [1]
A major section of an organism therefore might carry the same mutation, especially if that mutation occurs at earlier stages of development. [2] Somatic mutations that occur later in an organism's life can be hard to detect, as they may affect only a single cell—for instance, a post- mitotic neuron; [ 3 ] [ 4 ] improvements in single cell ...