This document discusses single nucleotide polymorphisms (SNPs), which are variations in DNA sequences among individuals. SNPs are the most common type of genetic variation, occurring around every 100 to 300 bases. They can be found in coding and non-coding regions, and may alter protein function directly by changing amino acids or indirectly by affecting regulatory sequences. SNPs can influence disease susceptibility and treatment response. Methods for identifying SNPs involve detecting known SNPs using techniques like restriction enzyme analysis or sequencing to find new SNPs. SNPs have many applications including gene mapping, disease association studies, diagnostics, and predicting treatment response.

1. PT.RAVISHANKAR SHUKLA UNIVERSITY
RAIPUR (CG)
SOS IN BIOTECHNOLOGY
SEMINAR ON
SINGLE NUCLEOTIDE
POLYMORPHISM

2. POLYMORPHISM
•Polymorphism is a genetic term that
means ‘many shapes’
•It is the ability to appear in different
form

3. SINGLE NUCLEOTIDE POLYMORPHISM
•Single nucleotide polymorphism or SNP
(pronounced “snips”), are the most
common type of genetic variation
among peoples.
•Each SNP represents a difference in a
single DNA building block, called a
nucleotide

4. •It is a DNA sequence variation occurring
when a single nucleotide A, T ,G, C in
the genome differs between members
of a species
•For ex. Two sequenced DNA fragments
from different individuals, AAGCCTA to
AAGCTTA , contain a difference in a
single nucleotide

6. SNPs FACTS
• SNP are found in coding (mostly) and non-coding regions.
• Occur with a very high frequency about 1 in 1000 bases
to 1 in 100 to 300 bases.
• The abundance of SNPs and the ease with which they can
be measured make these genetic variations significant.
• SNPs close to particular gene acts as a marker for that
gene.
• SNPs in coding regions may alter the protein structure
made by that coding region.

7. SNP MAPPING
•Sequence genome of a large number of
people.
•Compare the base sequences to
discover SNPs.
•Generate a single map of the human
genome containing all possible SNPs.

8. TYPES OF SNP
•Following are the types of SNP
Non-coding region
Coding region
-Synonymous
-Non-synonymous
Missense
Nonsense

9. •NON CODING REGION
A segment of DNA that does comprise a
gene and thus don’t code for a protein.
•CODING REGION
Regions of DNA/RNA sequences that code
for proteins

10. SYNONYMOUS
A SNP in which both forms lead to the same polypeptide
sequences is termed as synonymous(sometime called a
silent mutation).
NON SYNOYMOUS
If a different polypeptides sequences is produced they are
non synonymous. A non synonymous change may either be
missense or nonsense, where a missense change results in
a different amino acid, while a nonsense change results in
a premature stop codon.

11. EFFECT OF SNP
SILENT
Alter the function of the protein
•Directly ; alter an amino acid sequence
•Indirectly ; alter the function of the
regulatory sequences.

12. ROLE OF SNPs IN DISEASE PREDISPOSITION
•The Common Disease Are Multifactorial
•The genetic differences between
human populations make one
populations more susceptible to
particular disease.

13. SNPs AND CANCER
• SNPs in genes involved in DNA repair and drug
metabolizing enzymes which responsible for
metabolism & detoxification of carcinogens can
act as cancer susceptibility genes.
Trough
• Increase activation of chemical carcinogens.
• Decrease ability of cells to detoxify & repair
mutagenetic damage.

14. METHODS OF IDENTIFICATION SNPs
A.Detection of known SNPs
B.Identification of new SNPs

15. DETECTION OF KNOWN SNPs
• A) GEL-BASED GENOTYPING METHODS
1. PCR with restriction enzyme coupled analysis.
2. Amplification refractory mutation
systems(ARMS)
3. Oligonucleotide ligation assay.
4. Minisequencing.

16. DETECTION OF KNOWN SNPs
•B) NON GEL BASED HIGH THROUGHPUT
GENOTYPING TECHNOLOGIES
•1) hybridization using fluorescence
resonance energy transfer detection(Taq
man genotyping, Molecular beacons).
•2) high density chip array.

17. IDENTIFICATION OF NEW SNPs
•1) Conformation-based mutation
scanning.
•2) direct DNA sequencing.

18. Conformation-based mutation scanning.
•Single-strand conformation polymorphism
(SSCP).
- most widely used methods.
PRINCIPLE
Single strand DNA tend to fold into complex
structure which determines the mobility of
the DNA strand in non denaturing gel.

19. USE AND IMPORTANCE OF SNPs
•Variations in the DNA sequences of humans
can affect how many humans develop
diseases and respond to pathogens ,
chemical, drugs, vaccines, and other
agents.
•SNPs are also thought to be key enablers in
realizing the concept of personalized
medicine

20. APPLICATIONS
•Gene discovery and mapping
•Association based candidate polymorphism
testing
•diagnostics/risk profiling
•Response prediction
•Homogeneity testing/study design
•Gene function identification

21. CONCLUSION
• A single nucleotide polymorphism is a DNA
sequence variation occurring when a single
nucleotide genome differs between members of a
species.
• They can act as biological markers, helping
scientists locate genes that are associated with
disease. When SNPs occur within a gene or in
regulatory region near a gene, they may play a
more direct role in disease by affecting the genes
functions.

22. REFERENCES
• Gene cloning and DNA analysis 6 edition- T.A Brown
• https://ghr.nlm.nih.gov/primer/genomicresearch/snp
• https://en.wikipedia.org/wiki/Single-nucleotide_polymorphism
• https://www.youtube.com/watch?v=x4m1_P5Ljf8