Single Nucleotide Substitution
Single Nucleotide Substitution - Related Videos
04:32
Chip-in-a-Tube-Based Digital PCR for Quantification of Single Nucleotide Variants
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2025
This video demonstrates the utility of digital PCR in a chip-in-a-tube format for the detection of single nucleotide variations in DNA samples. A single PCR reaction is partitioned into chambers that act as independent PCR reactions, and the detection of fluorescence signals from the amplified targets in the chambers is used to compute the frequency of the variant allele in the sample.
01:05
Single Nucleotide Polymorphisms-SNPs
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2021
A single nucleotide polymorphism or SNP is a single nucleotide variation at a specific genomic position in a large population. It is the most prevalent type of sequence variation found in the human genome. Point mutations that occur in more than 1% of the population qualify as SNPs. These are present once every 1000 nucleotides on an average in the human genome. Replacement of a purine with another purine (A/G) or a pyrimidine with another pyrimidine (C/T) is known as a transition. In contrast,...
14:21
Nucleophilic Substitution
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2023
Source: Vy M. Dong and Daniel Kim, Department of Chemistry, University of California, Irvine, CA Nucleophilic substitution reactions are among the most fundamental topics covered in organic chemistry. A nucleophilic substitution reaction is one where a nucleophile (electron-rich Lewis base) replaces a leaving group from a carbon atom. SN1 (S = Substitution, N = Nucleophilic, 1 = first-order kinetics) SN2 (S = Substitution, N = Nucleophilic, 2 = second-order kinetics) This video will help to...
07:24
Genotyping Single Nucleotide Polymorphisms in the Mitochondrial Genome by Pyrosequencing
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Cited by 6 •
2023
Pyrosequencing assays enable the robust and rapid genotyping of mitochondrial DNA single nucleotide polymorphisms in heteroplasmic cells or tissues.
10:14
Object Substitution Masking
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2023
Source: Laboratory of Jonathan Flombaum—Johns Hopkins University Visual masking is a term used by perceptual scientists to refer to a wide range of phenomena in which in an image is presented but not perceived by an observer because of the presentation of a second image. There are several different kinds of masking, many of them relatively intuitive and unsurprising. But one surprising and important type of masking is called Object Substitution Masking. It has been a focus of research in vision...
FAQs
Its consequence depends strongly on where it occurs and how the replacement changes base pairing. In a coding region, the change may leave the encoded amino acid unchanged, alter one amino acid, or create a premature stop signal. A substitution outside coding sequence can instead influence regulation or splicing, so location is central to interpreting biological impact.
These categories describe different outcomes in a coding sequence. A synonymous substitution does not change the encoded amino acid, whereas a missense substitution changes one amino acid to another. A nonsense substitution introduces a stop signal. This classification helps researchers prioritize variants for further study, although the surrounding genetic context remains important for interpretation.
Replication errors, chemical damage, and imperfect repair can all leave an incorrect nucleotide in the DNA sequence. If the altered base is copied or retained rather than corrected, the change can become a stable genetic variant. Understanding its origin provides mechanistic context when researchers evaluate how a substitution arose and whether it may affect gene function.
A noncoding location does not automatically mean that a substitution has no consequence. The change may affect a regulatory sequence that controls gene activity or interfere with splicing, the process that helps produce a mature RNA message. Consequently, analysis must consider regulatory and RNA-processing effects, not only whether the protein-coding sequence changes.
They first consider the substitution's position and classify its possible consequence in a coding, noncoding, regulatory, or splicing-related context. Researchers can then examine its relevance to disease risk, inheritance, population variation, or a biological trait. When interpretation remains uncertain, experimental models help test whether the specific change contributes to the observed outcome.
Experimental models are especially useful when sequence analysis alone cannot establish whether a substitution is biologically important. By examining a model carrying the specific change, researchers can investigate whether it contributes to altered gene function, a biological trait, or a clinical condition. This evidence helps distinguish an associated variant from one that plays a contributing role.
Variant analysis can connect a substitution with disease-risk assessment and inheritance patterns. Researchers evaluate where the change occurs and what functional consequence it may have, then consider how it appears across individuals or populations. These findings can support inheritance analysis and population studies while contributing to personalized medicine when genetic differences are relevant to an individual.