Name: snps as genetic markers and variants
Uploaded: 2021-04-07T12:12:00.000Z
Duration: 1 min 5 s
Channel: JoVE
Description: Single nucleotide polymorphisms, or SNPs, are small DNA changes at one specific genomic position. They are the most common type of sequence variation in the human genome. A point mutation counts as an SNP when it appears in more than 1% of the population.

K12 Standards

Arizona Science Standards

High School

Life Science

HS.L3

HS.L3U3.26

Single Nucleotide Polymorphisms-SNPs

Lorsque plusieurs génomes humains sont comparés, des variations sont observées dans les séquences.
Les variations dues à la substitution d’un nucléotide sont appelées polymorphismes mononucléotidiques, ou SNP.
Les variations dues à l’insertion ou à la suppression d’une séquence de nucléotides de moins d’un kilobase de longueur sont appelées indel.
Si une insertion ou une délétion de nucléotides est copiée un nombre variable de fois dans le même génome, on parle de variation du nombre de copies ou CNV. Souvent, les CNV impliquent de grandes étendues d’ADN de plus d’un kilobase.
Un haplotype est un ensemble de gènes hérités d’un seul parent. Un génome peut être divisé en blocs d’haplotypes qui contiennent des grappes de polymorphismes.
Étant donné que peu de croisements se produisent entre les chromosomes homologues au cours de chaque méiose, les blocs d’haplotypes ont été hérités dans un groupe lié à travers les générations.

<ol>
	<li>Chanock, Stephen. « Gènes candidats et polymorphismes mononucléotidiques (SNP) dans l’étude de la maladie humaine. » Marqueurs de maladie 17, n° 2 (2001) : 89-98. <a href="https://downloads.hindawi.com/journals/dm/2001/858760.pdf">https://downloads.hindawi.com/journals/dm/2001/858760.pdf</a></li>
	<li>Gao, Rongsui, Wenhong Zu, Yang Liu, Junhua Li, Zeyao Li, Yanling Wen, Haiyan Wang et al. « Quasi-espèces du SRAS-CoV-2 révélées par l’analyse des polymorphismes nucléotidiques uniques (SNP). » Virulence 12, n° 1 (2021) : 1209-1226. <a href="https://www.tandfonline.com/doi/full/10.1080/21505594.2021.1911477">https://www.tandfonline.com/doi/full/10.1080/21505594.2021.1911477</a></li>
</ol>

polymorphismes nucléotidiques uniques-snp

Un polymorphisme nucléotidique unique ou SNP est une variation d'un seul nucléotide à une position génomique spécifique dans une grande population. Il s’agit du type de variation de séquence le plus répandu dans le génome humain. Les mutations ponctuelles qui surviennent chez plus de 1 % de la population sont considérées comme des SNP. Ceux-ci sont présents en moyenne une fois tous les 1000 nucléotides dans le génome humain. Le remplacement d'une purine par une autre purine (A/G) ou d'une pyrimidine par une autre pyrimidine (C/T) est appelé transition. En revanche, la substitution d'une purine par une pyrimidine (A ou G/C ou T) ou vice versa est appelée transversion. Dans les SNP, les transitions sont plus importantes que les transversions.

Différentes méthodes sont utilisées pour étudier les variations génétiques présentes dans le génome, également appelées génotypage. Contrairement aux SNP, les répétitions en tandem simples (STR) impliquent des répétitions di-, tri- ou tétranucléotidiques. Les scientifiques utilisent souvent le génotypage des SNP plutôt que des STR, car les SNP sont plus abondants et plus stables, et certains SNP affectent directement le phénotype.

La plupart du temps, les SNP se trouvent dans les introns, qui ne codent pour aucune protéine. De tels SNP peuvent être utilisés comme marqueurs biologiques pour localiser les gènes associés à une maladie particulière. Si le SNP est présent dans un gène ou dans une séquence régulatrice proche du gène, il peut affecter sa fonction et provoquer une maladie.

Polymorphismes nucléotidiques uniques-SNP

Un polymorphisme mononucléotidique, ou SNP, est une variation mononucléotidique à une position génomique spécifique dans une grande population. C’est le plus répandu ...

Education

Enseignement

JoVE Core

Molecular Biology

Biologie moléculaire

Unit 2

Unité 2

Analyzing Gene Expression and Function

Analyse de l'expression et de la fonction géniques

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

snps as genetic markers and variants

Single nucleotide polymorphisms, or SNPs, are small DNA changes at one specific genomic position. They are the most common type of sequence variation in the human genome. A point mutation counts as an SNP when it appears in more than 1% of the population.

SNPs as Genetic Markers and Variants

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Single nucleotide polymorphisms, or SNPs, are small DNA changes at one specific genomic position. They are the most common type of sequence variation in the human genome. A point mutation counts as an SNP when it appears in more than 1% of the population.

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key terms and concepts

Explore SNPs as common DNA variants, including transitions, transversions, and how they help scientists find genes linked to disease.

SNPs as Genetic Markers and Variants | JoVE K12

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SNPs as Genetic Markers and Variants

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