base substitution

base substitution

The replacement of a single nucleotide in a nucleic acid (e.g., in DNA or RNA) which can be silent—due to “degeneracy” of DNA, in which multiple codons encode the same amino acid—or result in a point mutation with a substituted amino acid or premature termination of transcription or translation.

base substitution

replacement of a NUCLEOTIDE base in a DNA molecule with another base, possibly producing a SUBSTITUTION MUTATION.
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The primer pair Mt-1 /4508R and template DNA from a patient known to carry the A4136G base substitution were used to make a 1379-bp product with nucleotide position 4136 located >300 by from one end.
The most common gene defect resulting in A1AT deficiency is that of a protease inhibitor (PI)-system Z mutation Glu342 to Lys, which is a single base substitution of G to A in exon 5 [4,5].
Using the new process, researchers reported that the error rate for DNA base substitution declined from 0.1 percent (1 in 1,000) to between 0.01 (1 in 10,000) and 0.001 percent (1 in 100,000).
TMB is the number of somatic, coding, base substitution, and indel mutations per megabase of the genome tested (3).
According to this agreement, there are 6 kinds of reasonable base substitution combinations (see Table 4).
We further investigated the type of mutation contained in the supF mutant colony using PCR and a subsequent sequencing analysis of the supF region and found that the percentage of mutant colonies containing a base substitution or one-base insertion/deletion at position 159 of supF was markedly higher in the 8BrG-containing pMY189 (22.4%) than in the wild-type pMY189 (1.1%) in H1299 cells (Figures 1(b) and 1(c)).
A 272 27 214 31 C 250 29 201 20 G 208 16 171 21 T 264 14 229 21 Total 994 86 815 93 Type of base substitution Mutated base Transition Transversion Ratio A 198 74 2.68 C 194 56 3.46 G 166 42 3.95 T 195 69 2.80 Total 753 241 3.12 Table 4: Spectrum of spontaneous mutations.
First, a codon is modified by base substitution from one coding for an amino acid such as glutamate, to a stop or termination codon ('null mutation' or 'nonsense mutation'); this type of mutation can result in a truncated protein with little natural function.
However the recognition of single base substitution as plausible explanation for unusual presentation of clinical syndromes at variance from an established paradigm might suggest race as a factor.
The first SNP was a base substitution (T[right arrow]C) at 367 bp of coding region in exon 2, which changed a leucine to a serine in protein sequence.
This led to the discovery of the base substitution in the SMPX gene in all of the family members affected by the hearing impairment.
Salmonella typhimurium strain TA100 differentiates several classes of carcinogens and mutagens by base substitution specificity.

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