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Silent mutations, also called synonymous or samesense mutations, are mutations in DNA that do not have an observable effect on the organism's phenotype. The phrase silent mutation is often used interchangeably with the phrase synonymous mutation ; however, synonymous mutations are not always silent, nor vice versa.
A point mutation is a genetic mutation where a single nucleotide base is changed, inserted or deleted from a DNA or RNA sequence of an organism's genome. [1] Point mutations have a variety of effects on the downstream protein product—consequences that are moderately predictable based upon the specifics of the mutation.
Point substitution mutations of a codon, classified by their impact on protein sequence. A synonymous substitution (often called a silent substitution though they are not always silent) is the evolutionary substitution of one base for another in an exon of a gene coding for a protein, such that the produced amino acid sequence is not modified.
Missense mutations differ from nonsense mutations since they are point mutations that exhibit a single nucleotide change to cause substitution of a different amino acid. A nonsense mutation also differs from a nonstop mutation , which is a point mutation that removes a stop codon.
After Muller's classification of gene mutation, an isomorph was described as a silent point mutant with identical gene expression as the original allele. [4] [5] m/Df = m/Dp Therefore, with respect to the relationship between the original and mutated genes, one cannot talk about the effects of dominance and/or recessiveness. [4] [5] [6]
It’s important to point out that the study just found a link between taking melatonin and the production of 8-OH-dG. It didn’t actually prove that people who took melatonin had better DNA repair.
Point mutations are a class of mutations which are changes to a single base. Missense , nonsense , and synonymous mutations are three subtypes of point mutations. The rate of these types of substitutions can be further subdivided into a mutation spectrum which describes the influence of the genetic context on the mutation rate.
Missense mutations in the MeCP2 protein can cause Rett syndrome, otherwise known as the RTT phenotype. [9] T158M, R306C and R133C are the most common missense mutations causing RTT. [9] T158M is a mutation of an adenine being substituted for a guanine causing the threonine at amino acid position 158 being substituted with a methionine. [10]